Our first article in this section is on enzyme kinetics. Enzymes are biological catalysts. They are specific to one type of reaction and to one or a small group of reactants called substrates. A catalyst speeds up the rate of a reaction without being changed itself. They are necessary as most biological reactions are very slow. Kinetics is the study of reaction rates. This will be considered in the context of enzymes where the rate of the reaction means the rate of product formation. In this article we will look at the physiology and clinical significance of enzyme kinetics. We will do this by considering how the structure of the enzyme affects its function, and consider the biochemistry behind enzyme catalysed reactions
Next we will consider the biology of enzyme inhibition. Enzymes are required for most, if not all, of the processes required for life. Enzymes catalyse a reaction by reducing the activation energy needed for the reaction to occur. However, enzymes need to be tightly regulated to ensure that levels of the product do not rise to undesired levels. This is accomplished by enzyme inhibition.
Reversible and irreversible inhibitors are chemicals which bind to an enzyme to suppress its activity. One method to accomplish this is to almost permanently bind to an enzyme. These types of inhibitors are called irreversible. However, other chemicals can transiently bind to an enzyme. These are called reversible. Reversible inhibitors either bind to an active site (competitive inhibitors), or to another site on the enzyme (non-competitive inhibitors). Competitive inhibitors compete with the substrate at the active site, and therefore increase Km (the Michaelis-Menten constant). However, Vmax is unchanged because, with enough substrate concentration, the reaction can still complete.