Horseshoe crab lactate dehydrogenase: tissue distribution and molecular weight.

Lactate dehydrogenase from Xiphosura (Limulus) polyphemus i D(-)-lactate specific. It does not use L(+)-lactate, alpha-hydroxybutyrate, alpha-hydroxyvalerate, or alpha-hydroxyisocaproate as substrate. In most tissues lactate dehydrogenase is composed of five isozymes with a molecular weight of 140,000 for each, as judged by gel-filtration chromatography. This suggests that the isozyme, are tetramers comprised of varying amounts of two physicochemically distinc subunits.