ABSTRACT
An enzyme has maximum activity only within a narrow pH range. The pH optimum of an enzyme is dependent on a number of experimental parameters, including time of reaction, temperature, nature and concentration of substrate, nature and concentration of buffer, ionic strength of medium, and purity of enzyme preparation, among others. The pH stability of an enzyme is modified by a number of factors. Consider, for example, the effect of pH on the stability of trypsin. A determination of the effect of pH on stability of an enzyme at 0°C cannot be extrapolated easily to 25 to 35°C. The effect of pH on enzyme stability is modified by other factors, such as buffer type and concentration, presence or absence of substrate, ionic strength and dielectric constant of the medium, and the effect of pH on the stability of cofactors and activators.
