The Comparative Enzymology of Triosephosphate Dehydrogenase.

The properties of crystalline rabbit muscle (1) and yeast (2) triosephosphate dehydrogenases have been studied extensively (3). Velick and Udenfriend (4) have compared some of the properties of the two enzymes. They reported that, although the two enzymes have similar molecular weights and similar amino acid distributions with only small variations, there are differences in the internal structure of the two proteins, since they possess different immunological (5)) physicochemical, and catalytic properties. Elodi et al. (6-10) have shown that the triosephosphate dehydrogenases isolated from five mammalian species (swine, cat, dog, rabbit, and beef) cannot be differentiated by immunochemical and serological studies, and that they possess identical physicochemical and catalytic properties; whereas the triosephosphate dehydrogenases isolated from two crustacean species show differences in these properties. A more complete survey of the properties of triosephosphate dehydrogenase was undertaken to see to what degree this enzyme has been altered during evolution. Crystalline rabbit, beef, human, chicken, turkey, pheasant, halibut, sturgeon, lobster, and yeast triosphosphate dehydrogenases and homogeneous Escherichia coli triosephosphate dehydrogenase were prepared. The sedimentation constants, electrophoretic properties, amino acid compositions, and reactivity with coenzyme analogues of these purified enzymes were compared. In addition, the dehydrogenases prepared from the various species have been characterized by immunological techniques.