Subcellular compartmentation of glycolytic intermediates in XXXX .

@entity33904 @entity653 @entity3177 @entity7685 @entity2388
In cell-fractionation experiments most of the glycolytic enzymes in bloodstream forms of @entity3177 are recovered in a microbody, called the glycosome [Opperdoes, F. R. and Borst, P. (1977) FEBS Lett. 80, 360-364]. To see whether this compartmentation of glycolytic enzymes is accompanied by compartmentation of metabolites we have pulse-labelled intact @entity3177 with [U-14C]glucose and followed the incorporation of radioactivity into glycolytic intermediates separated by anion-exchange chromatography. The kinetics of incorporation provide direct evidence for the existence of two pools of glycolytic intermediates. One pool is completely labelled within 15 s and represents 20-30% of total cellular metabolites. Radioactively labelled @entity2388 is already produced after 15 s. Since this pool is directly involved in the glycolytic flux, we conclude that it is present in the glycosome. The second pool which represents 70-80% of the total appears not to be directly involved in glycolysis. Its content equilibrates relatively slowly with the glycosomal pool. It probably represents the cytosol. Incorporation of radioactivity into the total @entity7685 pool is more rapid than for the other metabolites studied. This indicates rapid mixing of the glycosomal and cell-sap pools of @entity7685 , as required for the extra-glycosomal oxidation of @entity7685 by the mitochondrial oxidase. In the presence of 1 mM @entity33904 , which mimics anaerobiosis, the trypanosome produces equimolar amounts of @entity2388 and @entity653 . Labelling of @entity653 and @entity7685 proceeds at identical rates but at all times the specific activity of @entity653 is less than that of @entity7685 . This is compatible with our earlier proposal that @entity653 is made from @entity7685 by @entity653 kinase. We conclude that glycolysis in trypanosomes takes place in the glycosome and that the membrane of this organelle is poorly permeable to most glycolytic intermediates.
