Lactate dehydrogenase (LDH) is an enzyme found in nearly all living cells, where it plays a key role in cellular metabolism. Its primary function is to convert lactate to pyruvate and vice versa, as part of the process of anaerobic respiration. This reversible conversion is crucial in maintaining the balance of lactate and pyruvate, which are important intermediates in cellular energy production.
LDH is composed of four subunits, which can be combined in different arrangements to form five isoenzymes: LDH-1 to LDH-5. These isoenzymes have different distributions across various tissues and organs in the body. For instance, LDH-1 and LDH-2 are predominantly found in the heart and red blood cells, while LDH-5 is mainly present in the liver and skeletal muscle.