The control of pyruvate kinases of Escherichia coli: further studies of the enzyme activated by ribose-5-phosphate.
The pyruvate kinase activated by ribose-5-phosphate from Escherichia coli has been purified to homogeneity, taking advantage of the stabilization of the enzyme by its inhibitor phosphate and by thiol reagents. The native enzyme has a tetrameric quaternary structure which, while prone to dissociation under many conditions, remains intact in the presence of the above reagents. The enzyme was found to reactivate on dilution out of 8 M urea. Interestingly, the recovery of activity is greatly increased by phosphate, an allosteric inhibitor, but markedly reduced by the allosteric activator, ribose-5-phosphate, implying that it is harder for the enzyme to refold to a 'relaxed state.' Proteolysis studies indicate a more open structure in the presence of the activator.
D000494:Allosteric Regulation; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D046911:Macromolecular Substances; D010428:Pentosephosphates / Q000494:pharmacology*; D010710:Phosphates / Q000494:pharmacology; D011489:Protein Denaturation / Q000187:drug effects; D011770:Pyruvate Kinase / Q000302:isolation & purification / Q000378:metabolism*; D012267:Ribosemonophosphates / Q000494:pharmacology*; D014461:Ultracentrifugation
D008024:Ligands; D046911:Macromolecular Substances; D010428:Pentosephosphates; D010710:Phosphates; D012267:Ribosemonophosphates; D011770:Pyruvate Kinase