Enzyme kinetics - Dynamic of transformation

This article discusses the most useful and common kinetics observed in enzymology, as well as those that can be used to characterize new types of inhibitor. Particular kinetics obtained for complex enzyme systems, such as the proteasome, are not considered. The most commonly used mathematical treatments of data are also reviewed.

The work of Victor Henri and Adrian Brown at the beginning of the 20th century plotted the initial speeds obtained for an enzymatic reaction as a function of different substrate concentrations, and enabled experimental points to be fitted to a hyperbolic curve. In this way, the authors hypothesized the prior establishment of the enzyme-substrate reaction intermediate essential for the enzymatic reaction to proceed.

This hypothesis was revived by Michaelis and Menten, and later by Briggs and Haldane. However, the mathematical model obtained did not make it possible to explain the functioning of all enzymes. At the same time, Hill described that the oxygen uptake curve for hemoglobin (a non-enzymatic protein) as a function of oxygen partial pressure corresponded to a sigmoid curve. Subsequently, it was shown that protein catalysts were capable of transforming their substrate(s) following this same sigmoid pattern. It wasn't until the 1960s that Monod, Wyman and Changeux on the one hand, and Koshland on the other, proposed molecular models to explain allostery. Subsequently, more complex kinetics of substrate(s) transformation by enzymes were described.

At the end of the article, readers will find a glossary and a table of notations and symbols used.