Studies on fumarase. 3. The effect of temperature

Abstract

A study ofthe variation with temperature and pH of such properties of an enzyme as its maximum velocity and affinities for substrates and inhibitors might be expected to throw valuable light on the mechanism ofthe reaction catalysed by the enzyme. In this paper are reported some results on the variation of maximum velocity and Michaelis constants with temperature of crystalline fumarase, as well as the variation of Michaelis constants with pH. The variation of activity with pH in the presence of various salts has already been reported (Massey, 1952), and the variation of inhibitory constants of a number of dicarboxylic acids with both temperature and pH will be reported in a future paper. METHODS Fumarase. The fumarase solutions used were of twice recrystallized material obtained from pigs' hearts as already described (Massey, 1952).