ABSTRACT
Lactate dehydrogenase is one of the key enzymes in the glycolytic system and is ubiquitous to all animal cells. Lactate dehydrogenases from many animals and from different organs of the same animal have been purified and a number of their properties have been studied. One of the major reasons for this intensive effort is that lactate dehydrogenase occurs in multiple molecular forms and the relative amounts of these forms serve as a diagnostic tool for analyzing for several diseased states. The molecular weights of lactate dehydrogenases isolated from a great variety of animals and organs are invariant at 150,000. All lactate dehydrogenases are composed of four polypeptide chains of weight 37,500, and only the tetramer is enzymatically active. The sequences of amino acids around the active sites of triose phosphate dehydrogenase and horse liver and yeast alcohol dehydrogenases are different from those of lactate dehydrogenase.
