Mouse anti-PLDH monoclonal antibody for LFIA, Conjugation. Lactate dehydrogenase (LDH) is present in a wide variety of organisms, including plants and animals. It is an oxidoreductase which catalyses the interconversion of pyruvate and lactate with concomitant interconversion of NADH and NAD+. As it can also catalyze the oxidation of hydroxybutyrate, it is occasionally called Hydroxybutyrate Dehydrogenase (HBD). There are6different isoenzymes of LDH, LDH1 to LDH5, each composed of 4 subunits which may be of 2 different types - M and H subunits.