Antibodies against alcohol dehydrogenase and lactate dehydrogenase inhibit the activities of other unrelated NADH-requiring dehydrogenases.

Polyclonal rabbit antibodies to NADH-requiring enzymes such as yeast alcohol-dehydrogenase (ADH) and lactate-dehydrogenase (LDH) immunoinhibit the activities of other unrelated dehydrogenases. The immunoinhibition of malate-dehydrogenase (MDH) activity by anti-yeast ADH IgG and anti-hog LDH IgG was dependent on the concentration of antibodies and time. This demonstration of cross-reactivity with unrelated enzyme proteins reveals the existence of an antigenic site around the NADH binding region in each of these enzymes. Pre-treatment of the enzyme with NADH resulted in complete protection against immuno-inactivation. The competitive binding of NADH and the ineffectiveness of ATP establish the difference in the antigenic site around the NADH- and ATP-binding region.