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1. Mimicking Natural Photosynthesis: Designing Ultrafast Photosensitized Electron Transfer into Multiheme Cytochrome Protein Nanowires

   https://doi.org/10.3390/nano10112143  

   Marzolf, Daniel R. ; McKenzie, Aidan M. ; O’Malley, Matthew C. ; Ponomarenko, Nina S. ; Swaim, Coleman M. ; Brittain, Tyler J. ; Simmons, Natalie L. ; Pokkuluri, Phani Raj ; Mulfort, Karen L. ; Tiede, David M. ; et al ( November 2020 , Nanomaterials)

   Efficient nanomaterials for artificial photosynthesis require fast and robust unidirectional electron transfer (ET) from photosensitizers through charge-separation and accumulation units to redox-active catalytic sites. We explored the ultrafast time-scale limits of photo-induced charge transfer between a Ru(II)tris(bipyridine) derivative photosensitizer and PpcA, a 3-heme c-type cytochrome serving as a nanoscale biological wire. Four covalent attachment sites (K28C, K29C, K52C, and G53C) were engineered in PpcA enabling site-specific covalent labeling with expected donor-acceptor (DA) distances of 4–8 Å. X-ray scattering results demonstrated that mutations and chemical labeling did not disrupt the structure of the proteins. Time-resolved spectroscopy revealed three orders of magnitudemore »difference in charge transfer rates for the systems with otherwise similar DA distances and the same number of covalent bonds separating donors and acceptors. All-atom molecular dynamics simulations provided additional insight into the structure-function requirements for ultrafast charge transfer and the requirement of van der Waals contact between aromatic atoms of photosensitizers and hemes in order to observe sub-nanosecond ET. This work demonstrates opportunities to utilize multi-heme c-cytochromes as frameworks for designing ultrafast light-driven ET into charge-accumulating biohybrid model systems, and ultimately for mimicking the photosynthetic paradigm of efficiently coupling ultrafast, light-driven electron transfer chemistry to multi-step catalysis within small, experimentally versatile photosynthetic biohybrid assemblies.« less
2. Modernized uniform representation of carbohydrate molecules in the Protein Data Bank

   https://doi.org/10.1093/glycob/cwab039  

   Shao, Chenghua ; Feng, Zukang ; Westbrook, John D ; Peisach, Ezra ; Berrisford, John ; Ikegawa, Yasuyo ; Kurisu, Genji ; Velankar, Sameer ; Burley, Stephen K ; Young, Jasmine Y ( May 2021 , Glycobiology)

   Abstract Since 1971, the Protein Data Bank (PDB) has served as the single global archive for experimentally determined 3D structures of biological macromolecules made freely available to the global community according to the FAIR principles of Findability–Accessibility–Interoperability–Reusability. During the first 50 years of continuous PDB operations, standards for data representation have evolved to better represent rich and complex biological phenomena. Carbohydrate molecules present in more than 14,000 PDB structures have recently been reviewed and remediated to conform to a new standardized format. This machine-readable data representation for carbohydrates occurring in the PDB structures and the corresponding reference data improves the findability,more »accessibility, interoperability and reusability of structural information pertaining to these molecules. The PDB Exchange MacroMolecular Crystallographic Information File data dictionary now supports (i) standardized atom nomenclature that conforms to International Union of Pure and Applied Chemistry-International Union of Biochemistry and Molecular Biology (IUPAC-IUBMB) recommendations for carbohydrates, (ii) uniform representation of branched entities for oligosaccharides, (iii) commonly used linear descriptors of carbohydrates developed by the glycoscience community and (iv) annotation of glycosylation sites in proteins. For the first time, carbohydrates in PDB structures are consistently represented as collections of standardized monosaccharides, which precisely describe oligosaccharide structures and enable improved carbohydrate visualization, structure validation, robust quantitative and qualitative analyses, search for dendritic structures and classification. The uniform representation of carbohydrate molecules in the PDB described herein will facilitate broader usage of the resource by the glycoscience community and researchers studying glycoproteins.« less
3. Water and Life: The Medium is the Message

   https://doi.org/10.1007/s00239-020-09978-6  

   Frenkel-Pinter, Moran ; Rajaei, Vahab ; Glass, Jennifer B. ; Hud, Nicholas V. ; Williams, Loren Dean ( February 2021 , Journal of Molecular Evolution)

   Abstract Water, the most abundant compound on the surface of the Earth and probably in the universe, is the medium of biology, but is much more than that. Water is the most frequent actor in the chemistry of metabolism. Our quantitation here reveals that water accounts for 99.4% of metabolites in Escherichia coli by molar concentration. Between a third and a half of known biochemical reactions involve consumption or production of water. We calculated the chemical flux of water and observed that in the life of a cell, a given water molecule frequently and repeatedly serves as a reaction substrate, intermediate,more »cofactor, and product. Our results show that as an E. coli cell replicates in the presence of molecular oxygen, an average in vivo water molecule is chemically transformed or is mechanistically involved in catalysis ~ 3.7 times. We conclude that, for biological water, there is no distinction between medium and chemical participant. Chemical transformations of water provide a basis for understanding not only extant biochemistry, but the origins of life. Because the chemistry of water dominates metabolism and also drives biological synthesis and degradation, it seems likely that metabolism co-evolved with biopolymers, which helps to reconcile polymer-first versus metabolism-first theories for the origins of life.« less
4. Combining molecular visualization with bench methods in a hypothesis-driven undergraduate biochemistry lab course

   https://doi.org/10.1096/fasebj.30.1_supplement.666.2  

   Craig, Paul A ; Mills, Jeffrey L ; Daubner, Colette ; Pikaart, Michael J ( April 2016 , The FASEB journal)

   We are seeking to incorporate authentic inquiry into an undergraduate biochemistry lab course. Students on six campuses are combining computational (“in silico”) and wet lab (“in vitro”) techniques as they characterize proteins whose three dimensional structures are known but to which functions have not been previously ascribed. The in silico modules include protein visualization with PyMOL, structural alignment using Dali and ProMOL, sequence exploration with BLAST and Pfam, and ligand docking with PyRX and Autodock Vina. The goal is to predict the function of the protein and to identify the most promising substrates for the active sites. In the wetmore »lab, students express and purify their target proteins, then conduct enzyme kinetics with substrates selected from their docking studies. Their learning as students and their growth as scientists is being assessed in terms of research methods, visualization, biological context, and mechanism of protein function. The lab course is an extension of successful undergraduate research efforts at RIT and Dowling College. The modules that are developed will be disseminated to the scientific community via a web site (promol.org), including both protocols and captioned video instruction in the techniques involved. Over the course of the project, we will also be following changes in faculty and teaching assistant competence in two areas: effective teaching with structural biology tools and the development of skills in the area of measuring learning gains by students. As we conduct the lab on these different campuses, we will also focus on advantages of our approach and barriers to implementation that exist on each campus, from the level of student acceptance and faculty training, to resources that are needed to changes in the culture at the departmental and institutional levels. As we analyze the feasibility of this approach on other campuses, we will seek input from other potential adopters about their level of interest and the barriers that they anticipate on their campuses.« less
5. From Molecules to Molecular Surfaces. Exploiting the Interplay Between Organic Synthesis and Electrochemistry

   https://doi.org/10.1021/acs.accounts.9b00578  

   Jing, Q. ; Moeller, K. D. ( January 2020 , Accounts of chemical research)

   For many years, we looked at electrochemistry as a tool for exploring, developing, and implementing new synthetic methods for the construction of organic molecules. Those efforts examined electrochemical methods and mechanisms and then exploited them for synthetic gain. Chief among the tools utilized was the fact that in a constant current electrolysis the working potential at the electrodes automatically adjusted to the oxidation (anode) or reduction (cathode) potential of the substrates in solution. This allowed for a systematic examination of the radical cation intermediates that are involved in a host of oxidative cyclization reactions. The result has been a seriesmore »of structure-activity studies that have led to far greater insight into the behavior of radical cation intermediates and in turn an expansion in our capabilities of using those intermediates to trigger interesting synthetic reactions. With that said, the relationship between synthetic organic chemistry and electrochemistry is not a "one-way" interaction. For example, we have been using modern synthetic methodology to construct complex addressable molecular surfaces on electroanalytical devices that in turn can be used to probe biological interactions between small molecules and biological receptors in "real-time" as the interactions happen. Synthetic chemistry can then be used to recover the molecules that give rise to positive signals so that they can be characterized. The result is an analytical method that both gives accurate data on the interactions and provides a unique level of quality control with respect to the molecules giving rise to that data. Synthetic organic chemistry is essential to this task because it is our ability to synthesize the surfaces that defines the nature of the biological problems that can be studied. But the relationship between the fields does not end there. Recently, we have begun to show that work to expand the scope of microelectrode arrays as bioanalytical devices is teaching us important lessons for preparative synthetic chemistry. These lessons come in two forms. First, the arrays have taught us about the on-site generation of chemical reagents, a lesson that is being used to expand the use of paired electrochemical strategies for synthesis. Second, the arrays have taught us that reagents can be generated and then confined to the surface of the electrode used for that generation. This has led to a new approach to taking advantage of molecular recognition events that occur on the surface of an electrode for controlling the selectivity of a preparative reaction. In short, the confinement strategy developed for the arrays is used to insure that the chemistry in a preparative electrolysis happens at the electrode surface and not in the bulk solution. This account details the interplay between synthetic chemistry and electrochemistry in our group through the years and highlights the opportunities that interplay has provided and will continue to provide in the future.« less