Tricarboxylic acid and glyoxylate cycles in the Leishmaniae.

Cell-free extacts of four species of Leishmania (L. brasiliensis, L. donovani, L. mexicana and L. tropica) have been shown to contain all enzymes of the tricarboxylic acid cycle. However, the activity of citrate synthase is so low that it is doubtful whether this pathway is of significance in the metabolism of carbohydrate substrates. All four species show the presence of the two enzymes (isocitrate lyase and malate synthase) characteristic of the glyoxylate bypass and glyoxylate is present in cell-free preparations. The isocitrate lyase is relatively insensitive to phosphoenolpyruvate (PEP). The glyoxylate cycle in the Leishmaniae, thus, seems to be independent of control by C3 compounds.