Spotlights pubs.acs.org/JPCL
Spotlights: Volume 7, Issue 19
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ANOMALOUS DYNAMICS OF WATER CONFINED IN PROTEIN−PROTEIN AND PROTEIN−DNA INTERFACES Water is essential for living systems; active and versatile, it alters its characteristics to suit its environment. For example, confined water often exhibits anomalous properties not observable in the bulk phase. Although much is known about the behavior of water in hydrophobic confinement, the properties of water confined between hydrophilic surfaces, which are more frequently found in biological systems, has not been fully described. In their Letter, Chong and Ham (10.1021/ acs.jpclett.6b01858) used molecular dynamics simulations to investigate the dynamical properties of water confined in two of the most well studied hydrophilic protein−protein and protein−DNA systems, barnase−barstar and lac repressor− DNA. They found glassy slow relaxations even at 300 K and suggest that such sluggish water may play a key structural role in determining the stability and specificity of biomolecular assembly. The authors found that such slow water dynamics are induced by the hydrophilic binding surfaces, in opposition to the idea that the hydration water slaves protein motions. Their findings could significantly affect how we view the role of water in biomolecular interactions.
complementary measurements of individual nanoparticles while controlling the nanoparticle−electrode collision dynamics. The authors controlled the release of individual nanoparticles above a 400-nm-radius Au disk electrode and tuned the force acting on the particle upon its collision with the Au nanodisk. They show that high-velocity nanoparticle collisions result in a transient electrochemical redox event, whereas low-velocity collisions result in nanoparticle adsorption. These measurements are important for understanding the dynamical motion of nanoparticles near surfaces and how this motion affects chemical reactivity. The findings represent an advance in the study of the dynamics of particle collisions with electrified interfaces, which could lead to a better understanding of the relationship between nanoparticle size and electrochemical activity.
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DIRECT OXIDATIVE DAMAGE OF NAKED DNA GENERATED UPON ABSORPTION OF UV RADIATION BY NUCLEOBASES Ultraviolet radiation can cause genetic damage including DNA oxidation, which is seen in a variety of diseases and cancers. UV-induced formation of oxidative DNA has been thought to arise from the initial formation of singlet oxygen, produced by the excited DNA bases, but Gomez-Mendoza et al. (10.1021/ acs.jpclett.6b01781) use analytical methods to demonstrate that UV light (both UVC and UVB) is able to directly oxidize DNA through the transient formation of guanine radical cation. The authors found that polyamine-guanine adducts that are specifically produced through the transient formation of guanine radical cations are generated after UV irradiation of DNA in the presence of a polyamine even in the absence of any photosensitizer. Their findings show that not only UVC but also UVB light present in the solar spectrum reaching the Earth’s surface could directly oxidize DNA, thereby damaging the genetic code. Further research is needed to delineate the photochemical properties and chemistry of excited DNA bases, and this study may stimulate further theoretical and spectroscopic investigations in this area.
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GEOMETRY, SUPERTRANSFER, AND OPTIMALITY IN THE LIGHT HARVESTING OF PURPLE BACTERIA Nature has solved the problem of harvesting solar energy in many different ways, as evidenced by the bewildering diversity of light-harvesting antenna complexes in different photosynthetic organisms. The success of natural light harvesting raises hope that design principles could be extracted from it and used to improve artificial solar-energy conversion. By analyzing the robustness of the remarkably symmetric antenna complexes of purple bacteria to geometric perturbations, Baghbanzadeh and Kassal (10.1021/acs.jpclett.6b01779) identified evidence for the functional importance of coherence for the efficiency of biological light harvesting. The authors show that the geometry adopted by purple bacteria is more than 5 standard deviations better than what would be expected if the geometry were chosen by chance and that the enhancement can be attributed to supertransfer, a coherent, collective energy-transfer mechanism. Their results confirm the predicted importance of generalized Fö rster theory as one of the few coherent mechanisms possible in incoherent light, a finding that may be useful for future research in the areas of natural and artificial light harvesting.
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RESISTIVE PULSE DELIVERY OF SINGLE NANOPARTICLES TO ELECTROCHEMICAL INTERFACES In their Letter, McKelvey et al. (10.1021/acs.jpclett.6b01873) describe an experimental method for the delivery of individual nanoparticles to an electrochemical interface using a nanopipet resistive pulse system. Using two techniques, resistive pulse sensing (RPS) and the nanoparticle collision method, they took © 2016 American Chemical Society
Published: October 6, 2016 3989
DOI: 10.1021/acs.jpclett.6b02207 J. Phys. Chem. Lett. 2016, 7, 3989−3989
