Multiple alternative substrate kinetics.
The specificity of enzymes for their respective substrates has been a focal point of enzyme kinetics since the initial characterization of metabolic chemistry. Various processes to quantify an enzyme's specificity using kinetics have been utilized over the decades. Fersht's definition of the ratio kcat/Km for two different substrates as the "specificity constant" (ref [7]), based on the premise that the important specificity existed when the substrates were competing in the same reaction, has become a consensus standard for enzymes obeying Michaelis-Menten kinetics. The expansion of the theory for the determination of the relative specificity constants for a very large number of competing substrates, e.g. those present in a combinatorial library, in a single reaction mixture has been developed in this contribution. The ratio of kcat/Km for isotopologs has also become a standard in mechanistic enzymology where kinetic isotope effects have been measured by the development of internal competition experiments with extreme precision. This contribution extends the theory of kinetic isotope effects to internal competition between three isotopologs present at non-tracer concentrations in the same reaction mix. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment.
['Anderson|Vernon E|VE|']
D000465:Algorithms D055162:Biocatalysis D004798:Enzymes D007554:Isotopes D007700:Kinetics D008956:Models, Chemical D011485:Protein Binding D012313:RNA D043262:Ribonuclease P D013379:Substrate Specificity
Alternate substrate Alternate substrate Enzyme kinetics Specificity constant Combinatorial library Kinetic isotope effects Internal competition Alternative substrate Enzyme specificity