Abstract
Crystallized lipoamide dehydrogenase [EC 1.6.4.3] from Saccharomyces oviformis was found to be immunologically pure. The anti-enzyme antibody was readily formed by three or four subcutaneous injections of 3mg. of enzyme per week into rabbits. From the quantitative precipitin reaction, it was found that one mole of enzyme reacted with two moles of antibody at the equivalence zone of the antigen-antibody reaction. The NADH2-lipoamide and NADH2-menadione reductase activities decreased greatly when the enzyme combined with its antibody. However, the degree of inhibition did not change even when the enzyme reacted with more than two moles of antibody. The substrate NADH2 protected the enzyme slightly from inactivation by antibody. NAD had no protective effect.
The author wishes to thank Dr. G. Sunagawa, the Director of these Laboratories, for encouragement during this investigation and Dr. K. Nakanishi for valuable advice and discussion.
