Enzyme activities in the fat body of the tsetse fly Glossina morsitans and the fleshfly Sarcophaga tibialis in relation to proline metabolism

Abstract

Enzymes were assayed in the fat body of the tsetse fly Glossina morsitans and compared with those in the fat body of the fleshfly Sarcophaga tibialis. Alanine aminotransferase, 3-hydroxyacyl-CoA dehydrogenase, NADP-linked isocitrate dehydrogenase and proline synthetase were much more active in G. morsitans. NADP-linked malic enzyme, pyruvate carboxylase, citrate synthase and aconitase were also more active in G. morsitans, but α-oxoglutarate dehydrogenase, fumarase, malate dehydrogenase and various glycolytic enzymes were more active in S. tibialis. Pyruvate carboxylase was mainly mitochondrial in the fat body of both insects, whereas NADP-linked malic enzyme was cytoplasmic. Alanine aminotransferase and NADP-linked isocitrate dehydrogenase were more predominantly mitochondrial in G. morsitans than in S. tibialis. In the fat body of G. morsitans the View the MathML source values of pyruvate carboxylase for pyruvate and bicarbonate were quite low, whereas those of NADP-linked malic enzyme were high. Alanine aminotransferase from G. morsitans fat body had lower apparent View the MathML source values for alanine and α-oxoglutarate than flight muscle enzyme from the same species. The proline synthesizing potential of G. morsitans fat body is discussed. It is suggested that the pathway involves the enzymes pyruvate carboxylase and NADP-linked isocitrate dehydrogenase.