Glycolysis in <i>Trypanosoma brucei</i>

The possibility that the glycosomes present in the bloodstream form of Trypanosoma brucei [Opperdoes, F. R. and Borst, P. (1977) FEBS Lett. 80, 360–364] constitute a separate pool of glycolytic intermediates within the cell was investigated.In titrations of intact cells with digitonin, a differential activation of glycolytic enzymes was observed. Enolase, pyruvate kinase and the cell‐sap marker alanine aminotransferase were activated at 0.05 mg digitonin per mg protein. The nine glycosomal enzymes involved in the conversion of glucose and glycerol into 3‐phosphoglycerate were activated only at digitonin concentrations between 0.7 and 9.8 mg/mg protein. In subcellular fractions the activities of the latter enzymes were all latent between 70 and 92%. Latency was abolished by addition of 0.1% Triton X‐100 or partly by five cycles of freezing and thawing. We conclude that the glycosomal enzymes are surrounded by a membrane, which forms a permeability barrier to intermediates and co‐factors of glycolysis.The concentrations of glycolytic intermediates and of adenine nucleotides were measured under aerobic conditions as well as in the presence of 1 mM salicylhydroxamic acid, a respiratory