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Enzymes of Carbohydrate Metabolism in Four Human Species of Leishmania: A Comparative Survey *
Author(s) -
MARTIN ELMER,
SIMON MICHAEL W.,
SCHAEFER FRANK W.,
MUKKADA ANTONY J.
Publication year - 1976
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1976.tb03850.x
Subject(s) - biochemistry , pyruvate dehydrogenase phosphatase , branched chain alpha keto acid dehydrogenase complex , pyruvate decarboxylation , pyruvate dehydrogenase kinase , citric acid cycle , malate dehydrogenase , dehydrogenase , biology , oxoglutarate dehydrogenase complex , pyruvate dehydrogenase complex , lactate dehydrogenase , enzyme
SYNOPSIS. The occurrence and levels of activity of various enzymes of carbohydrate catabolism in culture forms (promastigotes) of 4 human species of Leishmania (L. brasiliensis, L. donovani, L. mexicana , and L. tropica ) were compared. These organisms possess enzymes of the Embden‐Meyerhof pathway but lack lactate dehydrogenase. No evidence could be found for the production of lactic acid by growing cultures and lactic acid could not be detected either in cell‐free preparations or after incubation of cell‐free extracts with pyruvate and NADH under appropriate conditions. All 4 species possess α‐glycerophosphate dehydrogenase and α‐glycerophosphate phosphatase which together could regenerate NAD, thus compensating for the absence of lactate dehydrogenase. The oxidative and nonoxidative reactions of the hexose monophosphate pathway are present in all 4 species. Cell‐free extracts have pyruvate dehydrogenase activity which allows the entry of pyruvate into and its subsequent oxidation through the tricarboxylic acid cycle. All enzymes of this cycle, including a thiamine pyrophosphate dependent α‐ketoglutarate dehydrogenase are present. Both NAD and NADP‐linked malate dehydrogenase activities are present. The isocitrate dehydrogenase is NADP specific. There is an active glutamate dehydrogenase which could compete with α‐ketoglutarate dehydrogenase for the common substrate (α‐ketoglutarate). Replenishment of C 4 acids is accomplished by heterotrophic CO 2 fixation catalyzed by pyruvate carboxylase. All 4 species have high levels of NADH oxidase activity. Several enzymes thus far not found in any species of Leishmania have been demonstrated. These are: phosphoglucose isomerase, triose phosphate isomerase, fructose‐1, 6‐diphosphatase, 3‐phosphoglycerate kinase, enolase, α‐glycerophosphate dehydrogenase, α‐glycerophosphate phosphatase, pyruvate dehydrogenase complex, citrate synthase, aconitase, α‐ketoglutarate dehydrogenase, glutamate dehydrogenase, and NADH oxidase.