title: Activation of spinach chloroplast NADP-linked glyceraldehyde-3-phosphate dehydrogenase by concerted hysteresis.
abstract: Kinetic analysis of glyceraldehyde-3-phosphate dehydrogenase showed that the enhancement of the NADP-linked activity by specific chloroplast modulators is a concerted process; either a selected second metabolite or the couple dithiothreitol/thioredoxin-f lowers the concentration of primary modulators (ATP, NADPH, inorganic phosphate, 1,3-diphosphoglycerate) required for maximal stimulation (A0.5). Organic solvents also stimulate NADP-glyceraldehyde-3-phosphate dehydrogenase in the absence of any modulator; the concentration for the highest specific activity correlates inversely with the respective octanol-water partition coefficient. On the other hand, alcohols also enhance enzyme activity by lowering the A0.5 for primary modulators. Another compound--spermine--inhibits both the ATP- and the inorganic phosphate-mediated activation, but it does not influence the NADPH-induced process.
mesh_terms: D000433:1-Propanol / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000438:Alcohols / Q000494:pharmacology; D054479:Chloroplast Thioredoxins; D002736:Chloroplasts / Q000201:enzymology*; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010940:Plant Proteins / Q000494:pharmacology; D010944:Plants / Q000201:enzymology; D012997:Solvents; D013096:Spermine / Q000494:pharmacology; D013879:Thioredoxins
chemical_list: D000438:Alcohols; D054479:Chloroplast Thioredoxins; D010710:Phosphates; D010940:Plant Proteins; D012997:Solvents; D013096:Spermine; D013879:Thioredoxins; D009249:NADP; D000255:Adenosine Triphosphate; D000433:1-Propanol; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D004229:Dithiothreitol