Isolation and kinetic properties of pyruvate kinase activated by fructose-1,6-biphosphate from Salmonella typhimurium LT-2.I.
Pyruvate kinase, activated by fructose-1,6-biphosphate from Salmonella typhimurium LT-2, has been isolated and purified to homogeneity. The enzyme, similar to that from Escherichia coli, is a tetramer with an approximate molecular weight of 240,000. The native enzyme shows optimum pH 6.8 (T = 30 degrees C). The enzymatic reaction does not require K+ ions; while Mg2+ or Mn2+ are essential for its activity. The non-activated enzyme shows sigmoid kinetics to phosphoenolpyruvate with a Hill coefficient of 2.73; the activated enzyme becomes michaelian with KSADP y KSPEP 0.25 and 0.08 mM, respectively. Both substrates excess and ATP cause enzyme inhibition. In agreement with the experimental results a steady-state random-ordered hybrid Bi-Bi mechanism with two dead-end complexes is proposed.
D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005635:Fructosediphosphates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008970:Molecular Weight; D011770:Pyruvate Kinase / Q000302:isolation & purification* / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D005635:Fructosediphosphates; D011770:Pyruvate Kinase; D008274:Magnesium; C029063:fructose-1,6-diphosphate