Life Sciences Commons^™

Special Issue: Intramolecular Hydrogen Bonding 2017, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Even after more than a century of study [1–6], scrutiny, and detailed examination, the H-bond continues [7–12] to evoke a level of fascination that surpasses many other phenomena. Perhaps it is the ability of the simple H atom, with but a single electron, to act as a glue that maintains contact between much more complicated species. Or it might be its geometry, which prefers to hold the bridging proton on a direct line between the two heavy atoms. Not to be ignored are the spectral features of the H-bond: the large red shift of the stretching frequency of the covalent …

A Bipyridine-Ligated Zinc(Ii) Complex With Bridging Flavonolate Ligation: Synthesis, Characterization, And Visible-Light-Induced Co Release Reactivity, Shayne Sorenson, Marina Popova, Atta M. Arif, Lisa M. Berreau

Chemistry and Biochemistry Faculty Publications

Metal-flavonolate compounds are of significant current interest as synthetic models for quercetinase enzymes and as bioactive compounds of importance to human health. Zinc-3-hydroxyflavonolate compounds, including those of quercetin, kampferol, and morin, generally exhibit bidentate coordination to a single ZnII center. The bipyridine-ligated zinc-flavonolate compound reported herein, namely bis(μ-4-oxo-2-phenyl-4H-chromen-3-olato)-κ3O3:O3,O4;κ3O3,O4:O3-bis[(2,2′-bipyridine-κ2N,N′)zinc(II)] bis(perchlorate), {[Zn2(C15H9O3)2(C10H8N2)2](ClO4)2}n, (1), provides an unusual example of bridging 3-hydroxyflavonolate ligation in a dinuclear metal complex. The symmetry-related ZnII centers of (1) exhibit a distorted octahedral geometry, with weak coordination of a perchlorate anion trans to the bridging deprotonated O atom of the flavonolate ligand. Variable-concentration conductivity measurements provide evidence that, when …

Unraveling The Interactions Of The Physiological Reductant Flavodoxin With The Different Conformations Of The Fe Protein In The Nitrogenase Cycle, Natasha Pence, Monika Tokmina-Lukaszewska, Zhi-Yong Yang, Rhesa N. Ledbetter, Lance C. Seefeldt, Brian Bothner, John W. Peters

Chemistry and Biochemistry Faculty Publications

Nitrogenase reduces dinitrogen (N2) to ammonia in biological nitrogen fixation. The nitrogenase Fe protein cycle involves a transient association between the reduced, MgATP-bound Fe protein and the MoFe protein and includes electron transfer, ATP hydrolysis, release of Pi, and dissociation of the oxidized, MgADP-bound Fe protein from the MoFe protein. The cycle is completed by reduction of oxidized Fe protein and nucleotide exchange. Recently, a kinetic study of the nitrogenase Fe protein cycle involving the physiological reductant flavodoxin reported a major revision of the rate-limiting step from MoFe protein and Fe protein dissociation to release of Pi. Because the Fe …

First-Row Transition Metal Sulfides And Phosphides As Competent Electrocatalysts For Water Splitting, Nan Jiang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Solar energy is a carbon-neutral and renewable energy resource. Its nature of intermittence and unequal distribution requires efficient solar energy capture, conversion, and storage. Solar-driven water splitting to produce hydrogen and oxygen is widely considered as an appealing approach to meet this goal, in which hydrogen acts as a green energy carrier. Water splitting consists of two redox half reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Both reactions involve the transfer of multiple electrons and protons and possess high energy barriers to proceed at appreciable rates, hence catalysts are needed.

A large number of HER and OER …

Mechanism Of Substrate Reduction By Nitrogenase, Nimesh Khadka

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen (N) is a vital element of life and the main component of chemical fertilizer. The industrial Haber-Bosch process fulfills the demands of today’s nitrogen need and is therefore considered as one of the major scientific breakthroughs of the last century. However, the Haber-Bosch process operates at very high temperature and pressure, and requires fossils fuels to drive the reaction, making it an energy expensive process. The energy demand for this process accounts for almost 3% of the total global energy consumption. In addition, the rapid population growth, economic development and depletion of limited non-renewable fossil fuels have already created …

Conservative Tryptophan Mutations In Protein Tyrosine Phosphatase Ptp1b And Its Effect On Catalytic Rate And Chemical Reaction, Teisha Richan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Protein-tyrosine phosphatases (PTPs) catalyze the hydrolysis of phosphorylated tyrosines by a 2-step mechanism involving nucleophilic attack by cysteine and general acid catalysis by aspartic acid. In most PTPs the aspartic acid resides on a flexible protein loop, consisting of about a dozen residues, called the WPD loop. PTP catalysis rates span several orders of magnitude, and differences in WPD loop dynamics have recently been show to correlate with the rate of enzymatic catalysis. The rate of WPD loop motion could possibly be related to a widely conserved tryptophan residue on the WPD loop. Therefore, point mutants were made in PTP1B …

Identifying Multiple Predictors Of Physical Rehabilitation Outcomes, Jacklyn M. Sullivan, Elizabeth B. Fauth, Sydney Y. Schaeffer

Research on Capitol Hill

Previous studies have suggested that disability in activities of daily living (ADLs) is an outcome of cognitive impairment, physical limitations, psychosocial factors, and environmental constraints. We hypothesis that cognitive abilities and psychosocial factors measured at admission can be used to predict a patients physical therapy progression in a transitional care facility. Environmental conditions were held constant for all patients and physical limitations were not used as a predictor of therapy progression, as the test for therapy progression is based on physical ability. In a sample of adults (n=93) aged 38-98 receiving physical rehabilitation treatment, we collected Minimum Data Set (MDS) …