[Enzyme kinetics for enzyme immunoassay].

The rate of reaction involving an enzyme is greatly influenced by temperature, pH, concentration of the substrate, and a number of other factors. Therefore, an accurate measurement of enzyme-catalyzed reaction is important for enzyme immunoassay. The substrate concentration needed for half-maximum velocity (1/2 Vmax) is called the Km value (Michaelis constant) and is expressed in units of substrate concentration (moles per liter or M). Km may be considered an approximate measure of affinity of an enzyme for its substrate: the lower the Km, the higher is the affinity. At times, optimum conditions cannot be used, and compromises in optimum assay conditions must be made.