Spotlights Cite This: J. Phys. Chem. Lett. 2018, 9, 1178−1178
pubs.acs.org/JPCL
Spotlights: Volume 9, Issue 5
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WHAT IS RESPONSIBLE FOR ATYPICAL DEPENDENCE OF THE RATE OF AMYLOID FORMATION ON PROTEIN CONCENTRATION: FIBRIL-CATALYZED INITIATION OF NEW FIBRILS OR COMPETITION WITH OLIGOMERS? Alzheimer’s disease is one of a number of devastating and fatal diseases that are associated with the formation of amyloid fibrils. Formation of amyloids is a special case of protein “misfolding”, when protein chains form fibrils with a cross-β structure instead of retaining their native globular structures or being natively disordered. There have been many studies of the kinetics of amyloid formation by various proteins under different conditions, and many hypotheses have been proposed to explain the mechanisms of fibril formation in general and that of amyloid fibrils in particular. In one study, an abnormal dependence of the rate of amyloid formation on protein concentration was observed for Aβ40 peptides associated with Alzheimer’s disease. Finkelstein et al. (10.1021/acs.jpclett.7b03442) offer an explanation of the observed anomalous kinetics: formation of metastable oligomers competing with fibril formation by decreasing the concentration of the fibrilforming free monomers. They show that the oligomer sizes resulting from the anomalous dependence of the fibril growth rate on protein concentration are close to the sizes of oligomers observed by electron microscopy.
strong electro-optic traits as a result of their distorted crystal structures, which lend them large nonlinear electronic susceptibilities and high sensitivities to field-induced displacements of the germanium atoms.
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HOW DETERGENT IMPACTS MEMBRANE PROTEINS: ATOMIC-LEVEL VIEWS OF MITOCHONDRIAL CARRIERS IN DODECYLPHOSPHOCHOLINE Understanding the function of membrane proteins (MP) at the atomic level is crucially important in the field of structural biology, but researchers in this area face many challenges. Characterizing the structure of MPs generally requires extraction from their native environment, but the detergents used for this purpose could alter the structural organization of the MPs themselves. The detergent dodecyphosphocholine (DPC) has been the most commonly used membrane mimetic in NMR spectroscopy studies to elucidate the structure, dynamics, and interactions of MPs, and the resulting structural and dynamical information has been interpreted as biologically relevant. For example, mitochondrial carriers solubilized in DPC detergent have been proposed to be of functional relevance, and their structures, interactions, and dynamics have been discussed. Kurauskas et al. (10.1021/acs.jpclett.8b00269) present an in-depth physicochemical study of mitochondrial carriers in DPC and show how seemingly biologically relevant samples turn out not to reflect functionally relevant conformations upon closer inspection. The authors combined NMR experiments with functional transport assays, molecular dynamics simulations, and thermostability experiments, and they report that the native properties of these proteins are indeed disrupted by the detergent environment. The results also shed light on the structural and dynamical properties of the resulting state. The findings add to our physicochemical understanding of detergent/membrane protein complexes and could help shape future studies of membrane proteins.
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LIGHT-HARVESTING STRATEGY DURING CO2-DEPENDENT PHOTOSYNTHESIS IN THE GREEN ALGA CHLAMYDOMONAS REINHARDTII Photosynthesis is an efficient process, and photosynthetic organisms maximize that efficiency by balancing their lightharvesting ability and CO2 use. Exactly how this happens remains unclear, so Ueno et al. (10.1021/acs.jpclett.7b03404) investigated the molecular mechanisms of light harvesting in the green alga Chlamydomonas reinhardtii under various CO2 conditions. They used a combination of pulse-amplitude modulated fluorescence, steady-state fluorescence with absolute intensity, and time-resolved fluorescence, and they concluded that two light-harvesting abilitiesmigration and aggregationof light-harvesting chlorophyll−protein complex II play an important role in the regulation of the light harvesting.
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ELECTRO-OPTIC RESPONSE IN GERMANIUM HALIDE PEROVSKITES The implementation of optical interconnects at small scales, such as for inter- or intrachip communications, necessitates the development of devices capable of converting electrical signals to optical signals at these scales. Walters and Sargent (10.1021/ acs.jpclett.7b03353) studied germanium halide perovskites, which, like lead halide perovskites, are solution-processed and thus compatible with advanced modulator designs. The feature that distinguishes germanium halide perovskites from other metal halide perovskites is their crystal structure, which meets the symmetry requirements for the electro-optic effect. The authors found that the germanium halide compounds possess © 2018 American Chemical Society
Published: March 1, 2018 1178
DOI: 10.1021/acs.jpclett.8b00557 J. Phys. Chem. Lett. 2018, 9, 1178−1178
