Secondary kinetic isotope effects (a-deuterium) have been explored as a method for delineating the nature of the transition state in enzyme-catalyzed reactions. Hen egg-white lysozyme and almond @-glucosidase were chosen as enzymes for these experiments. Initially, model studies were performed on the cleavage of phenyl glucosidic bonds in acid (SN1 mechanism) and in base (sN2 mechanism). The values obtained (kH/kD = 1.13 for sN1 mechanism, ka/ko = 1.03 for S N~ mechanism) were in the anticipated range. The value obtained for @-glucosidase-catalyzed hydrolysis of phenyl b-D-glucopyranoside was kA/kl) = 1.01, and this suggests a displacement mechanism for this enzyme. Such a result is in

No abstract

No abstract

No abstract

No abstract