Learn More
Biological catalysts (enzymes) speed up reactions by many orders of magnitude using fundamental physical processes to increase chemical reactivity. Hydrogen tunnelling has increasingly been found to contribute to enzyme reactions at room temperature. Tunnelling is the phenomenon by which a particle transfers through a reaction barrier as a result of its(More)
One of the most intriguing questions in modern enzymology is whether enzyme dynamics evolved to enhance the catalyzed chemical transformation. In this study, dihydrofolate reductase, a small monomeric protein that catalyzes a single C-H-C transfer, is used as a model system to address this question. Experimental and computational studies have proposed a(More)
The relationship between protein dynamics and function is a subject of considerable contemporary interest. Although protein motions are frequently observed during ligand binding and release steps, the contribution of protein motions to the catalysis of bond making/breaking processes is more difficult to probe and verify. Here, we show how the quantum(More)
Hydrogen quantum mechanical tunneling has been suggested to play a role in a wide variety of hydrogen-transfer reactions in chemistry and enzymology. An important experimental criterion for tunneling is based on the breakdown of the semiclassical prediction for the relationship among the rates of the three isotopes of hydrogen (hydrogen -H, deuterium -D,(More)
Biosynthesis of the DNA base thymine depends on activity of the enzyme thymidylate synthase to catalyse the methylation of the uracil moiety of 2'-deoxyuridine-5'-monophosphate. All known thymidylate synthases rely on an active site residue of the enzyme to activate 2'-deoxyuridine-5'-monophosphate. This functionality has been demonstrated for classical(More)
Previous studies of Escherichia coli dihydrofolate reductase (ecDHFR) have demonstrated that residue G121, which is 19 A from the catalytic center, is involved in catalysis, and long distance dynamical motions were implied. Specifically, the ecDHFR mutant G121V has been extensively studied by various experimental and theoretical tools, and the mutation's(More)
Nicotinamide containing cofactors are ubiquitous in biological systems. As a result, when studying nicotinamide dependent systems in vitro or in vivo, isotopically labeled nicotinamide cofactors are often used to reveal the mechanism of the biological system of interest. The reduced form of these cofactors is labile and is sensitive to light, oxygen, pH,(More)
CONSPECTUS: The role of the enzyme's dynamic motions in catalysis is at the center of heated contemporary debates among both theoreticians and experimentalists. Resolving these apparent disputes is of both intellectual and practical importance: incorporation of enzyme dynamics could be critical for any calculation of enzymatic function and may have profound(More)
The ThyA gene that encodes for thymidylate synthase (TS) is absent in the genomes of a large number of bacteria, including several human pathogens. Many of these bacteria also lack the genes for dihydrofolate reductase (DHFR) and thymidine kinase and are totally dependent on an alternative enzyme for thymidylate synthesis. Thy1 encodes flavin-dependent TS(More)
Three glycoforms of glucose oxidase, which vary in their degree of glycosylation and resulting molecular weight, have been characterized with regard to catalytic properties. Focusing on 2-deoxyglucose to probe the chemical step, we have now measured the temperature dependence of competitive H/T and D/T kinetic isotope effects and the enthalpy of activation(More)