The presence of alpha-glycerophosphate dehydrogenase (NAD+-linked) and adenylate kinase as core and integral membrane enzymes respectively in the glycosomes of Trypanosoma rhodesiense.
A subcellular fraction enriched 12 times in glycosomes (NAD+-linked alpha-glycerophosphate dehydrogenase) and devoid of detectable contamination from other subcellular components, was prepared from bloodstream Trypanosoma rhodesiense. Using a method employing exposure to toluene as a means of studying normally latent glycosomal enzymes, and phospholipase A2 as a membrane probe, the association of adenylate kinase and alpha-glycerophosphate dehydrogenase with the glycosome was studied. The normally latent glycerophosphate dehydrogenase (NAD+ linked), it is proposed, is an intraglycosomal enzyme having no membrane association, but bound to the core by weak ionic linkages. As such it is possible to release the enzyme from permeable (toluene treated) glycosomes using Cl-, with a resulting 4-fold increase in the Km for dihydroxyacetone phosphate. The presence of Cl- also stimulates an increase in specific activity, but this is observed before any release of enzyme. In contrast adenylate kinase, a non-latent glycosomal enzyme, is clearly membrane associated, the use of phospholipase A2 revealing an absolute dependence on phospholipid for activity. Restoration of activity appears to specifically require phosphatidyl choline and to be co-operative in nature (nH = 1.56). It is proposed that adenylate kinase is an integral glycosomal membrane enzyme, probably affecting the control of intra-glycosomal ADP/ATP levels.
McLaughlin
J
J
D000263:Adenylate Kinase / Q000378:metabolism*; D000818:Animals; D002458:Cell Fractionation; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology; D009940:Organoids / Q000201:enzymology; D010713:Phosphatidylcholines / Q000378:metabolism; D010740:Phospholipases; D010770:Phosphotransferases / Q000378:metabolism*; D014050:Toluene / Q000494:pharmacology; D014345:Trypanosoma / Q000201:enzymology* / Q000648:ultrastructure
D010713:Phosphatidylcholines; D014050:Toluene; D005993:Glycerolphosphate Dehydrogenase; D010770:Phosphotransferases; D000263:Adenylate Kinase; D010740:Phospholipases