Metal Binding to AÎ² Peptides Inhibits Interaction with Cytochrome c

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Article Cite This: ACS Omega 2018, 3, 13994−14003

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Metal Binding to Aβ Peptides Inhibits Interaction with Cytochrome c: Insights from Abiological Constructs Ankita Sarkar,† Kushal Sengupta,†,§ Sudipta Chatterjee,†,§ Manas Seal,† Peter Faller,‡ Somdatta Ghosh Dey,*,† and Abhishek Dey*,† †

Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A & 2B Raja S.C. Mullick Road, Kolkata 700032, India ‡ Biometals and Biology Chemistry, Institut de Chemie (CNRS UMR 7177), University of Strasbourg, 4 rue B. pascal, 67081 Strasbourg Cedex, France

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ABSTRACT: Aβ(1−40) peptide is mutated to introduce cysteine residue to allow formation of organized self-assembled monolayers (SAMs) on Au electrodes. Three mutants of this peptide are produced, which vary in the position of the inserted cysteine residue. Fourier transform infrared data on these peptide SAMs show the presence of both α helices and β sheet in these Aβ constructs. These peptide constructs interact with cytochrome c (Cytc), allowing electron transfer between Cytc and the electrode via the Aβ peptides. Binding of metals like Zn2+ or Cu2+ induces changes in the morphologies of these assemblies, making them fold, which inhibits their spontaneous interaction with Cytc.

1. INTRODUCTION Alzheimer’s disease (AD) is a common, progressive, fatal neurodegenerative disorder with enigmatic cause and cure.1 The disease becomes severe with age, and in its advanced stage, its pathological symptoms like confusion, memory loss, mood swing, declined thinking ability, and physical independence become prominent. Massive neuronal loss and disruption of synaptic function throughout the brain are hallmark physical characteristics of AD.2 All of the risk factors in AD are associated with abnormal production or clearance of amyloid β (Aβ) peptide, which is the prime constituent of extraneuronal senile plaques as well as intracellular neurofibrillary tangles.1,3 Aβ is a small peptide accommodating 39−42 amino acids and is derived from amyloidogenic proteolysis of the larger membrane-bound amyloid precursor protein (APP) by the combined action of β-secretase and γ-secretase.3−5 The most abundant fragments of this peptide are Aβ(1−40) and Aβ(1− 42). These peptides are bipolar with a hydrophilic N-terminus part (first 16 residues) and a hydrophobic C-terminus part (17−42 residues).6 Elevated concentrations of transition-metal ions Cu, Zn, and Fe in the neocortex of AD-affiliated brain advocate that metal dyshomeostasis is a major culprit in the pathogenesis of AD along with protein aggregation.3,7−11 The hydrophilic region of Aβ contains all of the metal-binding sites.12,13 A significant contribution of Zn2+ ions is found in the amyloidosis in transgenic mice, whereas the role of Cu is still ambiguous.14−17 In vitro, under physiological pH, redox-active metals like Cu © 2018 American Chemical Society

and Fe and cofactors like heme-bound Aβ peptides can catalyze the production of harmful reactive oxygen species (ROS) like O2−, O22−, and OH• through Fenton and Fentonlike chemistry.18−27 Overproduced27 amount of ROS initiates lipid peroxidation and nucleic acid adduct formation rendering extensive oxidative stress to the brain of AD patients.28−31 Abundance of high-molecular-weight Aβ fibrils in amyloid deposits initially implicated Aβ-mediated neurodegeneration in AD pathology. However, later studies and evidences enunciate that small soluble oligimeric form of Aβ is potentially more neurotoxic than insoluble larger Aβ aggregates.32−37 The extracellular amyloid plaque is classically considered as the histopathological marker of AD, but recent inspections have found that Aβ even triggers plaque-independent synaptic toxicity.38 This finding points the existence of intracellular pool of Aβ, which eventually elicits toxicity within the living cell much earlier than the appearance of extracellular senile plaque.39 The accumulation of Aβ in the cytosolic compartment is not surprising since its parental protein APP localizes to trans-Golgi network, endoplasmic reticulum, and endosomal, lysosomal, and mitochondrial membranes along with plasma membrane.40 Being a potent cytotoxic agent, Aβ also plays a dynamic role in apoptotic neuronal death although the obligate mechanism involved is ill-defined.41,42 On Aβ Received: July 21, 2018 Accepted: October 8, 2018 Published: October 25, 2018 13994

DOI: 10.1021/acsomega.8b01736 ACS Omega 2018, 3, 13994−14003

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Thus, the observed height of 8−12 nm for this assembly in AFM image is consistent with the fraction of a vertical assembly on the surface (approximately 3.3 Å × 38, i.e., 12 nm). Likewise, the height of the L17C assembly is almost half of the aforesaid assembly, i.e., 6−7 nm according to AFM image, which is also anticipated based on 3.3 Å linear translation per peptide residue. Methodically, the position of cysteine residue in Y10C places the height of this assembly (8−10 nm) in between that of G38C and L17C. This interpretation is evident from the following schematic representations of these mutants on Au surfaces (Figure 1)

exposure, mitochondria loses its morphological integrity and functionality, which highlights the localization of Aβ to the inner membrane or membrane-associated compartment of mitochondria and its deliberate interference with inner mitochondrial proteins.43−46 Several evidences suggest that Aβ-mediated cytochrome c oxidase (CcO) inhibition is an important contributor to the neurodegenerative cascade regarding AD.33,47 Additionally, our group has previously demonstrated the electron transfer between Cytc and heme− Aβ complexes.48,49 These emerging facts incite investigations into the possible interaction between Aβ and mitochondrial cytochrome c (Cytc). Cytc is a soluble hemoprotein found in the intermembrane space of mitochondria being loosely attached to the surface of inner mitochondrial membrane. It shuttles electrons from cytochrome bc1 (complex III) to CcO (complex IV) in the mitochondrial respiratory chain and also participates in ATP production.50 Moreover, Cytc is a prime required protein factor in programmed cell suicide and the load of translocated Cytc in the cytosol is a potential signal for regulation of cell apoptosis.51 Preponderance of structurally conserved lysine residues creates a large contiguous domain of surface positive charge around the heme crevice in the mitochondrial Cytc. This executive surface charge distribution provides the site of interaction to the heme prosthetic group of Cytc with corresponding prosthetic groups of its physiological oxidoreductases by complementary-charge reciprocation.52,53 Therefore, negatively charged Aβ is a potential candidate to interact spontaneously with Cytc, which shapes the basis of this current investigation. In the recent past, this group has established that human Aβ(1−16) forms self-assembled monolayer (SAM) on Au surfaces when appended with a cysteine residue at its 17th position and these constructs are demonstrated to survey the amount of ROS production by heme and Cu-bound Aβ peptides.54 These customized constructs have been also postulated to be an abiological platform to test potential drugs that could interact with Cu/heme active sites.54 Later, the controlled formation of small and large Aβ aggregates on Au surfaces has been reported resembling the oligomeric and fibrillar forms of Aβ, respectively. On Cu/heme binding, these morphologically different scaffolds appeared with discrete relative ROS generation property and also render distinct response to inhibitors like methylene blue and clioquinol analogue.55 The current report comprises the formation of morphologically different constructs on Au surfaces employing three customized mutants of Aβ(1−40) peptide, their structural as well as behavioral change on Cu/Zn binding, and how these changes affect the interaction of Aβ with Cytc.

Figure 1. Probable schematic representation of (a) G38C, (b) L17C, and (c) Y10C mutants of Aβ(1−40) on Au surfaces.

and the associated AFM images with their topological height distribution profiles (Figure 2). According to AFM images, these vertically upright Aβ assemblies on surfaces display smooth homogeneous distribution even in the absence of coadsorbant thiols. Cyclic voltammetry (CV) experiments with these G38C, L17C, and Y10C constructs in pH 7 phosphate-buffered solution show no redox response. However, when the same experiment is performed in the presence of 100 μM Bovine heart Cytc dissolved in pH 7 phosphate-buffered solution, a reversible process is found at 0.01 V vs Ag/AgCl and it is observed irrespective of the morphology of these Aβ assemblies (Figure 3). This process characterizes the oneelectron oxidation reduction of Cytc in solution, which originates from the heme prosthetic group of the protein representing the FeIII/II redox couple. We note that, in the presence of the same Cytc solution, bare Au electrode never shows any CV response (Figure S1). Therefore, it evidently suggests that electron transfer to heme of Cytc does not happen from barely exposed Au electrode, whereas Aβ adlayers on Au electrodes make this electron transfer possible. This phenomenon indicates that an interaction between Aβ and the protein may exist. Previously, our group has shown that reduced heme-Aβ transfers electron to oxidized Cytc, where docking of positively charged protein with the negatively charged Aβ was invoked to be responsible for such occurrence.48 In this current work, CV data suggests that Aβ adlayer plays an indispensable role in electron transfer from electrode to Cytc, which implies that an interaction between the protein and Aβ can lead to such an event. Since Aβ carries an overall negative charge of −3, it can approach the positivecharge domain of Cytc surface around its heme crevice through complementary-charge reciprocation and eventually the protein can dock with Aβ assemblies. The importance of carboxylate groups of Aβ functioning in the electron transfer between the electrode and Cytc has been supported employing nonamyloid constructs with discrete terminal groups. SAM of

2. RESULTS AND DISCUSSION Three Aβ(1−40) peptide mutants, prepared by introducing cysteine residue at different positions of the peptide chain by single-point mutation, are abbreviated as Aβ(1−40)Y10C (viz. Y10C), Aβ(1−40)L17C (viz. L17C), and Aβ(1−40)G38C (viz. G38C). These mutant peptides are immobilized on Au surfaces by means of SAM formation and found to exhibit different morphologies on the surfaces. The heights of these assemblies on Au surfaces are consistent with the number of amino acid residues present above the surface considering 3.3 Å linear translation per peptide residue, which is manifested in atomic force microscopy (AFM) analysis. In G38C, the cysteine is present almost at the end of the Aβ peptide chain. 13995


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represented in Scheme S1. We note that the proclaimed interaction between Cytc and Aβ is certainly electrostatic according to the previous report of our group, where Cytc and heme-Aβ were found to interact electrostatically.48 It is relevant to other literature reports also, where the interactions between Cytc and its other physiological oxidoreductases in mitochondria are mentioned as electrostatic.53 Binding of redox-active Cu2+ ion to Aβ constructs is already documented in previous reports.54−58 Currently, CV experiments with Cu-bound G38C-, L17C-, and Y10C-modified Au electrodes show quasi-reversible CuII/I process at 0.19, 0.17, and 0.08 V vs Ag/AgCl (Figure 4), respectively. We note that

Figure 4. CV responses of Cu-G38C (orange)-, Cu-L17C (green)-, and Cu-Y10C (light blue)-modified Au electrodes in pH 7 at 20 mV/s using Ag/AgCl reference and Pt wire counter electrodes.

different E1/2 values for these Cu-bound assemblies indicate that these immobilized mutants may offer different binding sites for Cu or they may have different environments around the same Cu-binding site. However, this is not the focus of the present report. From the CV data, coverage values of Cu (i.e., number of Cu ions per unit area) are calculated for all of these Cu-bound assemblies. The corresponding values for Cu-G38C, Cu-L17C, and Cu-Y10C constructs are 7.657 × 10−11, 2.756 × 10−11, and 1.672 × 10−11 mol/cm2.59−61 Since the average surface coverage of thiol SAM is of the order of 1014 molecules/cm2, the Cu sites present on these modified Au electrodes are thinly spread, which is also consistent with previous reports on Cu-Aβcys17 SAM-covered Au electrode.54,55 Unlike the previous observations in CV experiment with metal-free Aβ assemblies, these Cu-bound constructs do not exhibit the characteristic FeIII/II redox couple of Cytc even in the presence of Cytc dissolved in pH 7 phosphate-buffered solution but display another quasi-reversible process (Figure 5). Here, the CV responses may represent CuII/I redox couple, which are slightly altered compare to Figure 4 due to the presence of Cytc (Figure S3). This indicates the presence of an interruption of electron transfer from the electrode to the protein following binding of Cu to Aβ peptides. However, a possibility that the CuII/I process overlaps and envelopes the Cytc redox response prompted the use of redoxinactive Zn metal as a surrogate of Cu to perform similar experiments. Notably, Aβ assemblies upon binding Zn2+ ion do not show any CV response even in the presence of Cytc dissolved in pH 7 phosphate-buffered solution (Figure 6). It confirms that the electron transfer from the electrode to heme of the protein is no longer possible in the case of Zn-bound Aβ assemblies. This inference makes the accumulation of Zn/Cu to Aβ adlayers responsible for such an interruption of electron transfer and makes it only apparent that any form of

Figure 2. AFM images of (A) G38C-, (B) L17C-, and (C) Y10Cmodified Au surfaces with their respective topographic height distribution profiles (a), (b), and (c).

Figure 3. Blue, violet, and dark green lines, respectively, in (a), (b), and (c) designate the reversible FeIII/II process of Cytc on G38C-, L17C-, and Y10C-functionalized Au electrode, respectively, in pH 7 at 20 mV/s using Ag/AgCl reference and Pt wire counter electrodes.

1-octanethiol (C8SH SAM), which is devoid of any carboxylate group, does not show any redox response in the presence of Cytc, whereas such response appears when Au electrode covered with the SAM of 6-mercaptohexanoic acid (i.e., carboxylate SAM), which exclusively carries terminal carboxylate groups, was used (Figure S2). This divergence is also 13996


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intervals, while Aβ constructs are persistently incubated with pH 7 phosphate-buffered solution containing both Cytc and Zn2+ salt. Here, the CV current regarding FeIII/II redox couple of Cytc is found to decline gradually with time, and after a period, it completely disappears (Figure 7). We note that the

Figure 5. Blue, violet, and dark green lines in (a), (b), and (c) illustrate the corresponding CV responses of Cytc employing G38C-, L17C-, and Y10C-functionalized Au electrodes in pH 7 at 20 mV/s using Ag/AgCl reference and Pt wire counter electrodes. Further, red, light green, and light blue lines in (a), (b), and (c) indicate the corresponding CV responses of Cu-G38C, Cu- L17C, and Cu-Y10C constructs in the presence of Cytc dissolved in pH 7 buffered solution.

Figure 7. Zn binding assay of (a) G38C, (b) L17C, and (c) Y10C constructs with time monitoring the corresponding Cytc CV responses. Ipc (cathodic current of Cytc redox) and Iac (anodic current of Cytc redox) values are plotted against time. The blue, violet, and dark green indicators in (a), (b), and (c) represent the corresponding Ipc values, whereas the light green, light blue, and red indicators in (a), (b), and (c) represent the corresponding Iac values.

electrode here is not resistant to multiple scans (Figure S4). This observation indicates that metal binding blocks the transfer of electron from the electrode to the protein through the Aβ adlayer, which is possible only if Aβ loses its contact to the protein. It likely indicates that the residues responsible for the negative charge over Aβ peptide (i.e., the carboxylates of six amino acid residues in peptide chain) are no longer accessible to the positive-charge domain of Cytc after binding metal ions. Inhibition of electron transfer caused by participation of carboxylate groups has been established in Figure S5 using carboxylate SAM-covered Au electrode. To investigate the fate of Aβ assemblies upon metal binding, vibrational frequencies of these constructs are characterized by universal attenuated total reflection−Fourier transform infrared (UATR-FTIR) analysis before and after metal accumulation. We note that before metal binding, each construct illustrates amide I and amide II bands in the region of 1600− 1700 and 1500−1600 cm−1, respectively. Amide I is known to be originated predominantly from the skeletal amide −CO stretching vibrations of the peptide with minor contribution of C−N stretching, C−C−N deformation, and N−H in-plane bending. And amide II is known to carry signature of out-ofplane C−N stretching, N−H out-of-plane bending, and COO− asymmetric stretching vibrations. In this study, two broad spectra in these spectral regions indicate the occurrence of αhelical conformations (transmittance near 1650 cm−1) in these immobilized Aβ assemblies along with native β-sheet content (transmittance near 1630 cm−1).62−65 Upon Cu binding, a concomitant perturbation arises in these spectral regions (Figure S6). Involvement of the amino acid residues which

Figure 6. Blue, violet, and dark green lines, respectively, in (a), (b), and (c) illustrate CV responses of Cytc employing G38C, L17C, and Y10C-modified Au electrodes in pH 7 at 20 mV/s using Ag/AgCl reference and Pt wire counter electrodes. The corresponding light green, light blue, and red lines in (a), (b), and (c) represent CV responses of Zn-L17C, Zn-G38C, and Zn-Y10C constructs.

interaction between Cytc and Aβ is jeopardized on Zn/Cu binding. In the CV experiment with Zn-bound Aβ constructs, the CV of Cytc was not obtained when Aβ constructs were kept incubated with a solution of Zn(CH3COO)2·2H2O for 90 min. It implies that the Aβ assemblies may take around 90 min to completely accumulate Zn2+ ions and thus the change in the CV response of Cytc during this period is investigated. For this purpose, CV response of Cytc is monitored at several time 13997


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compose Cu coordinating domain in Aβ is believed to be responsible for such perturbation. We note that rationalization of frequency shifts upon metal binding is difficult due to the accompanying changes in the extent and nature of hydrogenbonding network of the peptide.66 However, a substantial drop in transmittance intensity is observed for each assembly upon Cu binding near 1265 cm−1, which classically represents the C−O stretch of C−OH vibration of a carboxylic acid group (Figure 8). It indicates that some of the side-chain carboxylates

Figure 9. (a) The blue line illustrates CV response of Cu-L17C construct in pH 7 buffered solution at 20 mV/s using Ag/AgCl reference and Pt wire counter electrodes. The red line illustrates the same when the construct was incubated with HQ solution for 60 min. (b) The particular peak near 1265 cm−1 in FTIR data representing −C−O single bond vibration of −C−OH group is shown in violet for L17C. The corresponding perturbation in transmittance of this particular peak for Cu-L17C construct and its restoration upon HQ exposure are clearly visible in light green and light blue.

Observations from CV and FTIR experiments prompt that metal binding may impose an alteration to Aβ adlayer. According to AFM images and the corresponding height distribution profiles, all Cu- and Zn-bound Aβ assemblies appear shorter compared to their metal-free analogues. The heights of Aβ constructs before metal binding and the corresponding changes upon Cu and Zn binding are summarized in Table 1. Figure 10 (right panel) and S7 in

Figure 8. The particular peak near 1265 cm−1 in FTIR data represents −C−O single-bond vibration of −C−OH group for (a) G38C (blue), (b) L17C (violet), and (c) Y10C (dark green) assembly. The corresponding perturbation in transmittance of this particular peak is clearly visible for (a) Cu-G38C (red), (b) Cu-L17C (light green), and (c) Cu-Y10C (light blue) constructs.

(these groups may remain H-bonded through salt-bridge interaction in peptide) in Aβ show bona fide participation in Cu coordination. This is consistent with the apical coordination of side-chain carboxylate to Cu as proposed in the literature.67−77 Similar observations were also found for Zn-bound peptide assemblies that reinforce the involvement of side-chain carboxylates toward metal binding validating the newly mentioned assignment in the present work.78 We note that HQ (8-hydroxyquinoline) being a clioquinol analogue is reported in the literature to sequestrate Cu from Cu-Aβ complexes in solution3,18,79 as well as from Cu-bound Aβ assemblies immobilized on Au surfaces.18,54,79 In this current work, HQ has been successfully used to sequestrate Cu from the Cu-Aβ constructs and it has been confirmed in CV experiment (Figure 9A). Following the protocol reported54,55 previously, Cu-L17C construct is immersed into 15 nM HQ solution and the corresponding UATR-FTIR data are collected. Here, transmittance intensity of the particular peak near 1265 cm−1, which is attributed to the C−O stretch of C− OH vibration, is found to be restored (Figure 9B). This suggests that the side-chain carboxylate involved in Cu binding returns to its previous form due to sequestration of Cu from Aβ assemblies. This phenomenon further validates the assignment of this observed vibrational band and the involvement of carboxylate in Cu coordination.

Table 1. Summary of Heights of Aβ Constructs before Metal Binding and Changes after Individual Binding of Cu and Zn to Those Assemblies Aβ constructs

G38C (nm)

L17C (nm)

Y10C (nm)

metal-free assemblies Cu-bound assemblies Zn-bound assemblies

8−12 5−6 4−6

6−7 4−5 5−6

8−10 4−5 5−6

the SI represent, respectively, the AFM images of Cu- and Znbound Aβ assemblies with their topological height distribution profiles. A comparison of metal-free Aβ constructs and their corresponding Cu-bound analogues is also given in Figure 10. The observed morphological changes of Aβ assemblies upon metal accumulation proposes that binding of metal to Aβ induces folding of the peptides, which results in shrinkage in the heights of the constructs. Moreover, growth in the CV current of CuII/I redox response is monitored at several intervals employing L17C construct incubated persistently with CuSO4 solution. From the corresponding coverage values of Cu at different intervals of incubation, the rate of Cu uptake by this construct is found to be 0.13 min−1. Meanwhile, decrease in the height of L17C assembly upon Cu binding is probed by AFM analysis at 13998


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Figure 10. Comparison of heights of Aβ constructs before metal binding and corresponding changes after binding of Cu to those assemblies observed in AFM images. (A), (B), and (C) represent, respectively, G38C-, L17C-, and Y10C-modified Au surfaces with their respective topographic height distribution profiles (a), (b), and (c). Similarly, (E), (F), and (G) represent, respectively, Cu-G38C-, Cu-L17C-, and Cu-Y10Cmodified Au surfaces with their respective topographic height distribution profiles (e), (f), and (g).

previously reported SAM formation technique. Different positions of introduced cysteine residues at these peptide chains lead to discrete morphologies on the surface. Unlike bare Au electrode, here the electrodes covered with these Aβ assemblies successfully transfer electron to heme of the Bovine heart Cytc, which declares prominent participation of Aβ adlayer in this process. There are several reports on Aβinduced mitochondrial membrane permeabilization, which leads to efflux of Cytc, but no direct interaction between Cytc and Aβ is evidenced to date.80−82 This current report refer that Cytc having positive-charge domain around its heme crevice can dock with negatively charged Aβ through electrostatic interaction. However, accumulation of metals like Cu/Zn to these Aβ assemblies mediates folding of Aβ peptides, which arrests all of the negatively charged residues (side-chain carboxylates of peptide) into the fold. It impairs the aforesaid electron transfer by blocking the proclaimed interaction between Aβ and the protein. Here, folding of Aβ is concurrent with its metal accumulation. Therefore, this present study employing an abiological platform reports an immediate interaction of Aβ with the electron-transfer protein Cytc and also suggests that Cu/Zn binding to Aβ inhibits that interaction, eventually leaving a scope to attenuate any possible Aβ-mediated toxicity to mitochondrial Cytc.

several intervals incubating this construct persistently with CuSO4 solution. The topological height distribution diagrams at different intervals of incubation postulates that the height of this assembly shrinks gradually over a period with simultaneous Cu uptake. The span of time this assembly takes to be shrunk in height is parallel to the rate of Cu uptake by this assembly (Figure 11). This observation suggests that Cu binding promotes concomitant folding of Aβ peptides immobilized on Au surfaces.

3. CONCLUSIONS In summary, three mutants of Aβ(1−40) peptides are immobilized on Au electrodes in this current work using

Figure 11. (a) Plot of coverage values of Cu against several intervals of incubation time of L17C assembly with solution of Cu observed in CV experiment. (b) Plot of average height distribution of L17C upon Cu binding in AFM against several intervals of incubation time of this assembly with solution of Cu.

4. EXPERIMENTAL SECTION 4.1. Materials and Methods. All reagents were of the highest grade commercially available and were used without purification. Aβ(1−40) peptides were purchased from 13999


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Zn-Aβ surfaces were prepared by incubation with the respective solutions over 90 min. After that period, the surfaces were rinsed with DMSO for 2 s to remove excess physiadsorbed Cu or Zn (if any) and dried by purging N2 gas. 4.4. Preparation of Cytc Solution. Cytc solution of 2−3 mM concentration was prepared by dissolving Bovin heart Cytc in pH 7 phosphate buffer. Then, the stock solution was diluted to 100 μM with pH 7 phosphate buffer and its exact concentration was determined from its absorbance at 550 nm for the completely reduced species. 4.5. Cyclic Voltammetry (CV) Experiments. CV data were collected in pH 7 phosphate buffer to obtain the redox potentials using modified electrodes. Bovine heart Cytc was dissolved in pH 7 phosphate buffer solution for all of the electrochemical experiments. For the time-dependent assay, a mixture of Cytc and Zn(OAc)2 was dissolved in phosphatebuffered solution and the final pH was maintained at 7. 4.6. Coverage Calculation. The coverage for a particular species is estimated by integrating the oxidation and reduction currents of the respective species. During this calculation, background currents of the constructs have been taken care of. 4.7. UATR-FTIR Experiments. Aβ as well as metal-bound Aβ-modified Au wafers were prepared as described in the previous sections. The surfaces were thoroughly rinsed with triple-distilled water and dried by purging N2 before analysis. Cu-bound Aβ-modified surfaces were immersed into 15 nM HQ solution in H2O for 1 h and then the surfaces were thoroughly rinsed with triple-distilled water followed by N2 purging. During the experiment, the MCT detector was maintained at a temperature of around 77 K.

GeneCust (Dudelange, Luxemburg) with a purity grade >95%. They were modified with cysteine at different positions by single-point mutation to acquire three different mutants. The amino acid sequence of these mutants is as follows. G38C (sequence: Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-GlyTyr-Glu-Val-His-His-Gln-Lys-Leu-Val-Phe-Phe-Ala-Glu-AspVal-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-CysVal-Val) L17C (sequence: Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-GlyTyr-Glu-Val-His-His-Gln-Lys-Cys-Val-Phe-Phe-Ala-Glu-AspVal-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-GlyVal-Val) Y10C (sequence: Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-GlyCys-Glu-Val-His-His-Gln-Lys-Leu-Val-Phe-Phe-Ala-Glu-AspVal-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-GlyVal-Val) Cytochrome c, from Bovine heart, BioChemika (≥95% (GE)); potassium hexaflurophosphate (KPF6) (≥99%); zinc acetate dihydrate (Zn(CH3COO)2·2H2O) (99.999% trace metal basis); 8-hyroxyquinoline (HQ) (99%), and 1octanethiol, 6-mercaptohexanoic acid were purchased from Sigma-Aldrich. Disodium hydrogen phosphate dihydrate (Na2HPO4·2H2O), copper sulfate pentahydrate (CuSO4· 5H2O), dimethyl sulfoxide (DMSO), chloroform, and absolute ethanol were purchased from Merck. Au wafers were purchased from Platypus Technologies. These wafers were made of 1000 Å of Au on 50 Å of Ti adhesion layer sited on the top of a Si (111) surface. 4.2. Instrumentation. All electrochemical experiments were performed using a CH Instruments (model CHI710D Electrochemical Analyzer). Counter electrodes, reference electrodes, and Teflon plate material were purchased from CH Instruments. The AFM data were obtained at room temperature in a Veeco dicp II (model no: AP-0100) instrument bearing a phosphate-doped Si cantilever (1−10 Ω cm; thickness, 3.5−4.5 μm; length, 115−135 μm; width, 30− 40 μm; resonance frequency, 245−287 kHz; elasticity, 20−80 N/m). FTIR data were obtained at room temperature in universal attenuated total reflection (UATR) setup of PerkinElmer using a mercury cadmium telluride (MCT) detector. 4.3. Construction of the Modified Electrodes. 4.3.1. Formation of Self-Assembled Monolayer (SAM). Gold wafers were cleaned electrochemically, first by electrolysis, where it was held at a high positive potential (2.1 V) for few seconds and then by sweeping several times between 1.8 and −0.3 V in 0.5 M H2SO4. Each mutant (G38C, L17C, Y10C) was weighed and taken individually in tripledistilled water to make 0.1 mM SAM solutions. Freshly cleaned Au wafers were thoroughly rinsed with triple-distilled water, purged with N2 gas, and then immersed in the SAM solutions for 2 days. To study aggregation properties by AFM and FTIR experiments, the surfaces were prepared similarly. Nonamyloid SAM solutions were prepared using 1 mM 1-octanethiol and 1 mM 6-mercaptohexanoic acid in absolute ethanol. 4.3.2. Attachment of Cu and Zn onto SAM. Gold wafers immersed in the SAM solutions were taken out and rinsed with triple-distilled water to remove excess adsorbate and dried with N2 gas to remove the residual solvent. The wafers were then inserted into plate material evaluating cell (ALS Japan). CuSO4·5H2O solution (10 mM) in DMSO and 10 mM Zn(CH3COO)2·2H2O solution in DMSO were used as the incubating solutions of Cu and Zn, respectively. Cu-Aβ and

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsomega.8b01736.

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CV of blank Au wafer in the absence and presence of Cytc (Figure S1); CV of Cytc in the presence of carboxylate SAM and C8SH SAM (Figure S2) and its schematic representation (Scheme S1); CV data comparing responses of Cytc with metal-free and Cubound constructs and response of Cu-bound constructs in the absence of Cytc (Figure S3); CV data describing that Au electrode is not resistant to multiple scans (Figure S4); CV data describing the engagement of carboxylate groups of Aβ in binding metals (Figure S5); UATR-FTIR data of metal-free and Cu-bound constructs representing amide I and amide II bands (Figure S6); AFM images and topographic height distribution profiles of Cu- and Zn-bound constructs (Figures S7 and S8, respectively) (PDF)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (S.G.D.). *E-mail: [email protected] (A.D.). ORCID

Sudipta Chatterjee: 0000-0003-4977-3840 Peter Faller: 0000-0001-8013-0806 Somdatta Ghosh Dey: 0000-0002-6142-2202 Abhishek Dey: 0000-0002-9166-3349 14000


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Beyreuther, K.; Zheng, H.; Tanzi, R. E.; Masters, C. L.; Bush, A. I. Treatment with a Copper-Zinc Chelator Markedly and Rapidly Inhibits β-Amyloid Accumulation in Alzheimer’s Disease Transgenic Mice. Neuron 2001, 30, 665−676. (19) Dikalov, S. I.; Vitek, M. P.; Mason, R. P. Cupric−amyloid β peptide complex stimulates oxidation of ascorbate and generation of hydroxyl radical. Free Radical Biol. Med. 2004, 36, 340−347. (20) Hu, W.-P.; Chang, G.-L.; Chen, S.-J.; Kuo, Y.-M. Kinetic analysis of β-amyloid peptide aggregation induced by metal ions based on surface plasmon resonance biosensing. J. Neurosci. Methods 2006, 154, 190−197. (21) Nelson, T. J.; Alkon, D. L. Oxidation of Cholesterol by Amyloid Precursor Protein and β-Amyloid Peptide. J. Biol. Chem. 2005, 280, 7377−7387. (22) Opazo, C.; Huang, X.; Cherny, R. A.; Moir, R. D.; Roher, A. E.; White, A. R.; Cappai, R.; Masters, C. L.; Tanzi, R. E.; Inestrosa, N. C.; Bush, A. I. Metalloenzyme-like Activity of Alzheimer’s Disease βAmyloid: Cu-dependent Catalytic Conversion of Dopamine, Cholesterol, and Biological Reducing Agents to Neurotoxic H2O2. J. Biol. Chem. 2002, 277, 40302−40308. (23) Tabner, B. J.; Turnbull, S.; El-Agnaf, O. M. A.; Allsop, D. Formation of hydrogen peroxide and hydroxyl radicals from Aβ and α-synuclein as a possible mechanism of cell death in Alzheimer’s disease and Parkinson’s disease. Free Radical Biol. Med. 2002, 32, 1076−1083. (24) Huang, X.; Atwood, C. S.; Hartshorn, M. A.; Multhaup, G.; Goldstein, L. E.; Scarpa, R. C.; Cuajungco, M. P.; Gray, D. N.; Lim, J.; Moir, R. D.; Tanzi, R. E.; Bush, A. I. The Aβ Peptide of Alzheimer’s Disease Directly Produces Hydrogen Peroxide through Metal Ion Reduction. Biochemistry 1999, 38, 7609−7616. (25) Pramanik, D.; Ghosh, C.; Dey, S. G. Heme−Cu Bound Aβ Peptides: Spectroscopic Characterization, Reactivity, and Relevance to Alzheimer’s Disease. J. Am. Chem. Soc. 2011, 133, 15545−15552. (26) Atamna, H.; Frey, W. H. A role for heme in Alzheimer’s disease: Heme binds amyloid β and has altered metabolism. Proc. Natl. Acad. Sci. USA 2004, 101, 11153−11158. (27) Stefan, C.; Fabrice, C.; Pierre, D.; Jerome, G.; Christelle, H.; Peter, F. Copper and Heme-Mediated Abeta Toxicity: Redox Chemistry, Abeta Oxidations and Anti-ROS Compounds. Curr. Top. Med. Chem. 2012, 12, 2573−2595. (28) Pramanik, D.; Ghosh, C.; Mukherjee, S.; Dey, S. G. Interaction of amyloid β peptides with redox active heme cofactor: Relevance to Alzheimer’s disease. Coord. Chem. Rev. 2013, 257, 81−92. (29) Ghosh, C.; Seal, M.; Mukherjee, S.; Ghosh Dey, S. Alzheimer’s Disease: A Heme−Aβ Perspective. Acc. Chem. Res. 2015, 48, 2556− 2564. (30) Markesbery, W. R.; Lovell, M. A. Four-Hydroxynonenal, a Product of Lipid Peroxidation, is Increased in the Brain in Alzheimer’s Disease. Neurobiol. Aging 1998, 19, 33−36. (31) Gabbita, S. P.; Lovell, M. A.; Markesbery, W. R. Increased Nuclear DNA Oxidation in the Brain in Alzheimer’s Disease. J. Neurochem. 1998, 71, 2034−2040. (32) Crouch, P. J.; Harding, S.-M. E.; White, A. R.; Camakaris, J.; Bush, A. I.; Masters, C. L. Mechanisms of Aβ mediated neurodegeneration in Alzheimer’s disease. Int. J. Biochem. Cell Biol. 2008, 40, 181−198. (33) Crouch, P. J.; Blake, R.; Duce, J. A.; Ciccotosto, G. D.; Li, Q.X.; Barnham, K. J.; Curtain, C. C.; Cherny, R. A.; Cappai, R.; Dyrks, T.; Masters, C. L.; Trounce, I. A. Copper-Dependent Inhibition of Human Cytochrome c Oxidase by a Dimeric Conformer of Amyloidβ 1−42. J. Neurosci. 2005, 25, 672−679. (34) Hartley, D. M.; Walsh, D. M.; Ye, C. P.; Diehl, T.; Vasquez, S.; Vassilev, P. M.; Teplow, D. B.; Selkoe, D. J. Protofibrillar Intermediates of Amyloid β-Protein Induce Acute Electrophysiological Changes and Progressive Neurotoxicity in Cortical Neurons. J. Neurosci. 1999, 19, 8876−8884. (35) Lambert, M. P.; Barlow, A. K.; Chromy, B. A.; Edwards, C.; Freed, R.; Liosatos, M.; Morgan, T. E.; Rozovsky, I.; Trommer, B.; Viola, K. L.; Wals, P.; Zhang, C.; Finch, C. E.; Krafft, G. A.; Klein, W.

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Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (K.S.) (S.C.). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors acknowledge Department of Science and Technology (DST) Grant EMR/2014/000392 (S.G.D.) and Grant SB/S1/IC-25/2013 (A.D.), Government of India, for funding this research. A.S. acknowledges DST-INSPIRE, India, and M.S. acknowledges Int. PhD programme of Indian Association for the Cultivation of Science for research fellowships.

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REFERENCES

(1) Rauk, A. The chemistry of Alzheimer’s disease. Chem. Soc. Rev. 2009, 38, 2698−2715. (2) Pramanik, D.; Dey, S. G. Active Site Environment of HemeBound Amyloid β Peptide Associated with Alzheimer’s Disease. J. Am. Chem. Soc. 2011, 133, 81−87. (3) Greenough, M. A.; Camakaris, J.; Bush, A. I. Metal dyshomeostasis and oxidative stress in Alzheimer’s disease. Neurochem. Int. 2013, 62, 540−555. (4) Cole, S. L.; Vassar, R. The Role of Amyloid Precursor Protein Processing by BACE1, the β-Secretase, in Alzheimer Disease Pathophysiology. J. Biol. Chem. 2008, 283, 29621−29625. (5) Steiner, H.; Fluhrer, R.; Haass, C. Intramembrane Proteolysis by γ-Secretase. J. Biol. Chem. 2008, 283, 29627−29631. (6) Savelieff, M. G.; DeToma, A. S.; Derrick, J. S.; Lim, M. H. The Ongoing Search for Small Molecules to Study Metal-Associated Amyloid-β Species in Alzheimer’s Disease. Acc. Chem. Res. 2014, 47, 2475−2482. (7) Kepp, K. P. Bioinorganic Chemistry of Alzheimer’s Disease. Chem. Rev. 2012, 112, 5193−5239. (8) Bush, A. I. The Metal Theory of Alzheimer’s Disease. J. Alzheimer’s Dis. 2013, 33, S277−S281. (9) Bush, A. I.; Masters, C. L.; Tanzi, R. E. Copper, β-amyloid, and Alzheimer’s disease: Tapping a sensitive connection. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 11193−11194. (10) Bush, A. I. The metallobiology of Alzheimer’s disease. Trends Neurosci. 2003, 26, 207−214. (11) Smith, D. G.; Cappai, R.; Barnham, K. J. The redox chemistry of the Alzheimer’s disease amyloid β peptide. Biochim. Biophys. Acta, Biomembr. 2007, 1768, 1976−1990. (12) Gaggelli, E.; Kozlowski, H.; Valensin, D.; Valensin, G. Copper Homeostasis and Neurodegenerative Disorders (Alzheimer’s, Prion, and Parkinson’s Diseases and Amyotrophic Lateral Sclerosis). Chem. Rev. 2006, 106, 1995−2044. (13) Kowalik-Jankowska, T.; Ruta, M.; Wiśniewska, K.; Łankiewicz, L. Coordination abilities of the 1−16 and 1−28 fragments of βamyloid peptide towards copper(II) ions: a combined potentiometric and spectroscopic study. J. Inorg. Biochem. 2003, 95, 270−282. (14) Zou, J.; Kajita, K.; Sugimoto, N. Cu2+ Inhibits the Aggregation of Amyloid β-Peptide(1−42) in vitro. Angew. Chem., Int. Ed. 2001, 40, 2274−2277. (15) Arena, G.; Pappalardo, G.; Sovago, I.; Rizzarelli, E. Copper(II) interaction with amyloid-β: Affinity and speciation. Coord. Chem. Rev. 2012, 256, 3−12. (16) Bush, A. I. Metal complexing agents as therapies for Alzheimer’s disease. Neurobiol. Aging 2002, 23, 1031−1038. (17) Cuajungco, M. P.; Fagét, K. Y. Zinc takes the center stage: its paradoxical role in Alzheimer’s disease. Brain Res. Rev. 2003, 41, 44− 56. (18) Cherny, R. A.; Atwood, C. S.; Xilinas, M. E.; Gray, D. N.; Jones, W. D.; McLean, C. A.; Barnham, K. J.; Volitakis, I.; Fraser, F. W.; Kim, Y.-S.; Huang, X.; Goldstein, L. E.; Moir, R. D.; Lim, J. T.; 14001


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Article

L. Diffusible, nonfibrillar ligands derived from Aβ1−42 are potent central nervous system neurotoxins. Proc. Natl. Acad. Sci. USA 1998, 95, 6448−6453. (36) Walsh, D. M.; Hartley, D. M.; Kusumoto, Y.; Fezoui, Y.; Condron, M. M.; Lomakin, A.; Benedek, G. B.; Selkoe, D. J.; Teplow, D. B. Amyloid β-Protein Fibrillogenesis: Structure and Biological Activity of Protofibrilar Intermediates. J. Biol. Chem. 1999, 274, 25945−25952. (37) LaFerla, F. M.; Green, K. N.; Oddo, S. Intracellular amyloid-β in Alzheimer’s disease. Nat. Rev. Neurosci. 2007, 8, 499−509. (38) Mucke, L.; Masliah, E.; Yu, G.-Q.; Mallory, M.; Rockenstein, E. M.; Tatsuno, G.; Hu, K.; Kholodenko, D.; Johnson-Wood, K.; McConlogue, L. High-Level Neuronal Expression of Aβ 1−42 in Wild-Type Human Amyloid Protein Precursor Transgenic Mice: Synaptotoxicity without Plaque Formation. J. Neurosci. 2000, 20, 4050−4058. (39) Du Yan, S.; Fu, J.; Soto, C.; Chen, X.; Zhu, H.; Al-Mohanna, F.; Collison, K.; Zhu, A.; Stern, E.; Saido, T.; Tohyama, M.; Ogawa, S.; Roher, A.; Stern, D. An intracellular protein that binds amyloid-β peptide and mediates neurotoxicity in Alzheimer’s disease. Nature 1997, 389, 689−695. (40) Kinoshita, A.; Fukumoto, H.; Shah, T.; Whelan, C. M.; Irizarry, M. C.; Hyman, B. T. Demonstration by FRET of BACE interaction with the amyloid precursor protein at the cell surface and in early endosomes. J. Cell Sci. 2003, 116, 3339−3346. (41) Troy, C. M.; Rabacchi, S. A.; Friedman, W. J.; Frappier, T. F.; Brown, K.; Shelanski, M. L. Caspase-2 Mediates Neuronal Cell Death Induced by β-Amyloid. J. Neurosci. 2000, 20, 1386−1392. (42) Sakono, M.; Zako, T. Amyloid oligomers: formation and toxicity of Aβ oligomers. FEBS J. 2010, 277, 1348−1358. (43) Calkins, M. J.; Reddy, P. H. Amyloid beta impairs mitochondrial anterograde transport and degenerates synapses in Alzheimer’s disease neurons. Biochim. Biophys. Acta, Mol. Basis Dis. 2011, 1812, 507−513. (44) Caspersen, C.; Wang, N.; Yao, J.; Sosunov, A.; Chen, X.; Lustbader, J. W.; Xu, H. W.; Stern, D.; McKhann, G.; Yan, S. D. Mitochondrial Aβ: a potential focal point for neuronal metabolic dysfunction in Alzheimer’s disease. FASEB J. 2005, 19, 2040−2041. (45) Manczak, M.; Anekonda, T. S.; Henson, E.; Park, B. S.; Quinn, J.; Reddy, P. H. Mitochondria are a direct site of Aβ accumulation in Alzheimer’s disease neurons: implications for free radical generation and oxidative damage in disease progression. Hum. Mol. Genet. 2006, 15, 1437−1449. (46) Cha, M.-Y.; Han, S.-H.; Son, S. M.; Hong, H.-S.; Choi, Y.-J.; Byun, J.; Mook-Jung, I. Mitochondria-Specific Accumulation of Amyloid β Induces Mitochondrial Dysfunction Leading to Apoptotic Cell Death. PLoS One 2012, 7, No. e34929. (47) Hernandez-Zimbron, L. F.; Luna-Muñ oz, J.; Mena, R.; Vazquez-Ramirez, R.; Kubli-Garfias, C.; Cribbs, D. H.; Manoutcharian, K.; Gevorkian, G. Amyloid-β Peptide Binds to Cytochrome C Oxidase Subunit 1. PLoS One 2012, 7, No. e42344. (48) Ghosh, C.; Mukherjee, S.; Dey, S. G. Direct electron transfer between Cyt c and heme-Aβ relevant to Alzheimer’s disease. Chem. Commun. 2013, 49, 5754−5756. (49) Seal, M.; Ghosh, C.; Basu, O.; Dey, S. G. Cytochrome c peroxidase activity of heme bound amyloid β peptides. J. Biol. Inorg. Chem. 2016, 21, 683−690. (50) Gonzales, D. H.; Neupert, W. Biogenesis of mitochondrialctype cytochromes. J. Bioenerg. Biomembr. 1990, 22, 753−768. (51) Liu, X.; Kim, C. N.; Yang, J.; Jemmerson, R.; Wang, X. Induction of Apoptotic Program in Cell-Free Extracts: Requirement for dATP and Cytochrome c. Cell 1996, 86, 147−157. (52) Zaidi, S.; Hassan, M. I.; Islam, A.; Ahmad, F. The role of key residues in structure, function, and stability of cytochrome-c. Cell Mol. Life Sci. 2014, 71, 229−255. (53) Salemme, F. R. Structure and Function of Cytochromes C. Annu. Rev. Biochem. 1977, 46, 299−330. (54) Pramanik, D.; Sengupta, K.; Mukherjee, S.; Dey, S. G.; Dey, A. Self-Assembled Monolayers of Aβ peptides on Au Electrodes: An

Artificial Platform for Probing the Reactivity of Redox Active Metals and Cofactors Relevant to Alzheimer’s Disease. J. Am. Chem. Soc. 2012, 134, 12180−12189. (55) Sengupta, K.; Chatterjee, S.; Pramanik, D.; Dey, S. G.; Dey, A. Self-assembly of stable oligomeric and fibrillar aggregates of A[small beta] peptides relevant to Alzheimer’s disease: morphology dependent Cu/heme toxicity and inhibition of PROS generation. Dalton Trans. 2014, 43, 13377−13383. (56) Trujano-Ortiz, L. G.; González, F. J.; Quintanar, L. Redox Cycling of Copper−Amyloid β 1−16 Peptide Complexes Is Highly Dependent on the Coordination Mode. Inorg. Chem. 2015, 54, 4−6. (57) Jiang, D.; Men, L.; Wang, J.; Zhang, Y.; Chickenyen, S.; Wang, Y.; Zhou, F. Redox Reactions of Copper Complexes Formed with Different β-Amyloid Peptides and Their Neuropathalogical Relevance. Biochemistry 2007, 46, 9270−9282. (58) Balland, V.; Hureau, C.; Savéant, J.-M. Electrochemical and homogeneous electron transfers to the Alzheimer amyloid-β copper complex follow a preorganization mechanism. Proc. Natl. Acad. Sci. USA 2010, 107, 17113−17118. (59) Kadish, K. M.; Frémond, L.; Ou, Z.; Shao, J.; Shi, C.; Anson, F. C.; Burdet, F.; Gros, C. P.; Barbe, J.-M.; Guilard, R. Cobalt(III) Corroles as Electrocatalysts for the Reduction of Dioxygen: Reactivity of a Monocorrole, Biscorroles, and Porphyrin−Corrole Dyads. J. Am. Chem. Soc. 2005, 127, 5625−5631. (60) Wei, J.; Liu, H.; Dick, A. R.; Yamamoto, H.; He, Y.; Waldeck, D. H. Direct Wiring of Cytochrome c’s Heme Unit to an Electrode: Electrochemical Studies. J. Am. Chem. Soc. 2002, 124, 9591−9599. (61) Ferrero, V. E. V.; Andolfi, L.; Di Nardo, G.; Sadeghi, S. J.; Fantuzzi, A.; Cannistraro, S.; Gilardi, G. Protein and Electrode Engineering for the Covalent Immobilization of P450 BMP on Gold. Anal. Chem. 2008, 80, 8438−8446. (62) Sarroukh, R.; Goormaghtigh, E.; Ruysschaert, J.-M.; Raussens, V. ATR-FTIR: A “rejuvenated” tool to investigate amyloid proteins. Biochim. Biophys. Acta, Biomembr. 2013, 1828, 2328−2338. (63) Cerf, E.; Sarroukh, R.; Tamamizu-Kato, S.; Breydo, L.; Derclaye, S.; Dufrêne, Y. F.; Narayanaswami, V.; Goormaghtigh, E.; Ruysschaert, J.-M.; Raussens, V. Antiparallel β-sheet: a signature structure of the oligomeric amyloid β-peptide. Biochem. J. 2009, 421, 415−423. (64) Sarroukh, R.; Cerf, E.; Derclaye, S.; Dufrêne, Y. F.; Goormaghtigh, E.; Ruysschaert, J.-M.; Raussens, V. Transformation of amyloid β(1−40) oligomers into fibrils is characterized by a major change in secondary structure. Cell Mol. Life Sci. 2011, 68, 1429− 1438. (65) Griffith, E. C.; Vaida, V. In situ observation of peptide bond formation at the water−air interface. Proc. Natl. Acad. Sci. USA 2012, 109, 15697−15701. (66) Bair, M. L.; Larsen, E. M. Glycine and leucine peptide complexes of copper, nickel, and zinc. J. Am. Chem. Soc. 1971, 93, 1140−1148. (67) El Khoury, Y.; Dorlet, P.; Faller, P.; Hellwig, P. New Insights into the Coordination of Cu(II) by the Amyloid-B 16 Peptide from Fourier Transform IR Spectroscopy and Isotopic Labeling. J. Phys. Chem. B 2011, 115, 14812−14821. (68) Conte-Daban, A.; Borghesani, V.; Sayen, S.; Guillon, E.; Journaux, Y.; Gontard, G.; Lisnard, L.; Hureau, C. Link between Affinity and Cu(II) Binding Sites to Amyloid-β Peptides Evaluated by a New Water-Soluble UV−Visible Ratiometric Dye with a Moderate Cu(II) Affinity. Anal. Chem. 2017, 89, 2155−2162. (69) Dorlet, P.; Gambarelli, S.; Faller, P.; Hureau, C. Pulse EPR Spectroscopy Reveals the Coordination Sphere of Copper(II) Ions in the 1−16 Amyloid-β Peptide: A Key Role of the First Two NTerminus Residues. Angew. Chem. 2009, 121, 9437−9440. (70) Mukherjee, S.; Ghosh, C.; Seal, M.; Dey, S. G. Copper induced spin state change of heme-Aβ associated with Alzheimer’s disease. Dalton Trans. 2017, 46, 13171. (71) Curtain, C. C.; Ali, F.; Volitakis, I.; Cherny, R. A.; Norton, R. S.; Beyreuther, K.; Barrow, C. J.; Masters, C. L.; Bush, A. I.; Barnham, K. J. Alzheimer’s Disease Amyloid-β Binds Copper and Zinc to 14002


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Generate an Allosterically Ordered Membrane-penetrating Structure Containing Superoxide Dismutase-like Subunits. J. Biol. Chem. 2001, 276, 20466−20473. (72) Guilloreau, L.; Damian, L.; Coppel, Y.; Mazarguil, H.; Winterhalter, M.; Faller, P. Structural and thermodynamical properties of CuII amyloid-β16/28 complexes associated with Alzheimer’s disease. J. Biol. Inorg. Chem. 2006, 11, 1024−1038. (73) Streltsov, V. A.; Titmuss, S. J.; Epa, V. C.; Barnham, K. J.; Masters, C. L.; Varghese, J. N. The Structure of the Amyloid-beta Peptide High-Affinity Copper II Binding Site in Alzheimer Disease. Biophys. J. 2008, 95, 3447−3456. (74) Karr, J. W.; Szalai, V. A. Role of Aspartate-1 in Cu(II) Binding to the Amyloid-β Peptide of Alzheimer’s Disease. J. Am. Chem. Soc. 2007, 129, 3796−3797. (75) Ghosh, C.; Dey, S. G. Ligand-Field and Ligand-Binding Analysis of the Active Site of Copper-Bound Aβ Associated with Alzheimer’s Disease. Inorg. Chem. 2013, 52, 1318−1327. (76) Alies, B.; Bijani, C.; Sayen, S.; Guillon, E.; Faller, P.; Hureau, C. Copper Coordination to Native N-Terminally Modified versus FullLength Amyloid-β: Second-Sphere Effects Determine the Species Present at Physiological pH. Inorg. Chem. 2012, 51, 12988−13000. (77) Gomez-Castro, C. Z.; Vela, A.; Quintanar, L.; Grande-Aztatzi, R.; Mineva, T.; Goursot, A. Insights into the Oxygen-Based Ligand of the Low pH Component of the Cu2+-Amyloid-β Complex. J. Phys. Chem. B 2014, 118, 10052−10064. (78) Alies, B.; Conte-Daban, A.; Sayen, S.; Collin, F.; Kieffer, I.; Guillon, E.; Faller, P.; Hureau, C. Zinc(II) Binding Site to the Amyloid-β Peptide: Insights from Spectroscopic Studies with a Wide Series of Modified Peptides. Inorg. Chem. 2016, 55, 10499−10509. (79) Opazo, C.; Luza, S.; Villemagne, V. L.; Volitakis, I.; Rowe, C.; Barnham, K. J.; Strozyk, D.; Masters, C. L.; Cherny, R. A.; Bush, A. I. Radioiodinated clioquinol as a biomarker for β-amyloid: Zn2+ complexes in Alzheimer’s disease. Aging Cell 2006, 5, 69−79. (80) Rodrigues, C. M.; Solá, S.; Silva, R.; Brites, D. Bilirubin and amyloid-beta peptide induce cytochrome c release through mitochondrial membrane permeabilization. Mol. Med. 2000, 6, 936−946. (81) Kim, J.; Yang, Y.; Song, S. S.; Na, J.-H.; Oh, K. J.; Jeong, C.; Yu, Y. G.; Shin, Y.-K. Beta-Amyloid Oligomers Activate Apoptotic BAK Pore for Cytochrome c Release. Biophys. J. 2014, 107, 1601−1608. (82) Kim, H.-S.; Lee, J.-H.; Lee, J.-P.; Kim, E.-M.; Chang, K.-A.; Park, C. H.; Jeong, S.-J.; Wittendorp, M. C.; Seo, J.-H.; Choi, S.-H.; Suh, Y.-H. Amyloid β peptide induces cytochrome c release from isolated mitochondria. NeuroReport 2002, 13, 1989−1993.

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Metal Binding to AÎ² Peptides Inhibits Interaction with Cytochrome c

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