The inhibition of d-glyceraldehyde 3-phosphate dehydrogenase by specific antiserum

Antibodies to yeast d-glyceraldehyde 3-phosphate dehydrogenase have been produced in rabbits and chickens. The antiserum from either animal inhibits the activity of the yeast enzyme with the formation of a precipitate that has a low residual activity. One combining site of antibody on the enzyme appears to be the point of DPN attachment. The rate of antigen-antibody formation has been studied with varying concentrations of antibody. The activity of yeast hexokinase is not inhibited by the antiserum to the dehydrogenase. Five of six antisera to the yeast enzyme showed no inhibition of the analogous enzyme from rabbit muscle, but one serum strongly inhibited the muscle dehydrogenase in the absence of DPN. No evidence was obtained that the inhibition by this one antiserum was due to an immune reaction, because the inhibition persisted after absorption with the homologous antigen.