Comparative study of Leishmania mexicana and Trypanosoma brucei NAD-dependent glycerol-3-phosphate dehydrogenase

The NAD-dependent glycerol-3-phosphate dehydrogenases (G3PDH EC 1.1.1.8) of Trypanosoma brucei and Leishmania mexicana ale thought to have different r oles in carbohydrate metabolism. Here the physicochemical and kinetic prope rties of natural G3PDH from T. brucei with the recombinant homologue of L. mexicana which share 63% positional identity ale compared. Despite their su pposed different functions in energy metabolism of the parasites the two G3 PDHs have remarkably similar properties, including pH optima and K-m value for dihydroxyacetone phosphate (DHAP) and NADH in the formation of glycerol 3-phosphate (G3P) and for NAD(+) and G3P in the reverse reaction. Both enz ymes are subject to substrate inhibition by dihydroxyacetone phosphate at c oncentrations above 0.2 mM and are inhibited by the trypanocidal drugs sura min and melarsen oxide at sub-micromolar concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.