ABSTRACT
Temperature modification as a means of controlling rates of enzyme-catalyzed reactions is very important. Control of temperature is a prerequisite for reproducible analyses of enzyme activity. The decrease in rate at higher temperatures is a result of temperature on stability of the enzyme, while the increase in rate at the lower temperatures is due to the effect of temperature on increasing the rate of conversion of substrate to product. The effect of temperature on stability of an enzyme can be determined readily. At a temperature below the temperature optimum, little if any denaturation of the enzyme will be observed, particularly if initial rates are used. Enzymes such as polyphenol oxidase, lipoxygenase, and glucose oxidase require O2 as one of the substrates. In general, activation energies for transformation of reactants to products in enzyme-catalyzed reactions are within the range 6000 to 15,000 cal/mol while activation energies for denaturation of enzymes are within the range 50,000 to 150,000 cal/mol.
