THE TEMPERATURE COEFFICIENT AND THE APPARENT ENERGY OF ACTIVATION OF THE ENZYMATIC HYDROLYSIS OF ARGININE; WITH ADDITIONAL OBSERVATIONS UPON THE STABILITY OF ARGINASE UNDER VARIOUS CONDITIONS

¹ The Institute of Physiology, University of Glasgow

The temperature coefficient of the arginine-arginase reaction at a pH of 7·35 varies from 2·70 for 0°-10° to about 1·54 for 40°-50°. At pH 9·85 it is smaller, and falls from 2·34 for 0°-10° to 1·73 for 20 °-30°. The calculated energies of activation corresponding range from 15,200 to 8660 and from 13,000 to 9600. Incidental observations have emphasised the great lability of the enzyme, and particularly its susceptibility to heat, in alkaline media. Its relative stability near the neutral point has been confirmed, although even there it has been found to undergo gradual destruction at temperatures as low as 30°.