Abstract
The author discusses the salient data bearing 1) upon the reversible inactivation by oxidation-reduction and by mercaptide-forming reagents of specified hydrolytic enzymes, presumably through reversible chemical actions upon substituent thiol groups of these enzymes; 2) upon the role of specific metal-coordinative processes in the reversible inactivation of arginase; 3) upon the role of reversible oxidation-reduction and dissociable metal complexes in the control of the kinetics of certain biological hydrolytic processes. The observations and interpretations have been considered with respect to several related problems of general physiological interest.