The Effects of Temperature Changes on Salivary Amylase Activity

Abstract

Salivary amylase from mixed human saliva detd. by Somogyi'' s iodine method and diluted finally 1:4000 with 0.25% NaCl at a pH of 6.8 showed an optimum activity at 50[degree] C. The increase in activity with a rise in temp. in the range below 50[degree] C is due to the accelerating effect of temp. on the native amylase-starch reaction. The heat of activation of this process was detd. to be 22,742 calories. The decrease in activity as the temp. is raised beyond the optimum is due to the ascendency of a denaturation reaction. The heat of activation of the process was detd. to be 62,342 calories. One stage of the heat denaturation is found to be reversible by cooling. The presence of substrate protects the enzyme against denaturation by altering the equilibrium between native and reversibly denatured enzyme in favor of the native form. NaCl effectively protects against the heat denaturation of salivary amylase.