The regulatory properties of yeast pyruvate kinase. Effect of pH.
The kinetics of pyruvate kinase from Saccharomyces cerevisiae were studied at 25 degrees C as a function of the concentrations of the substrates ADP, phosphoenolpyruvate and Mg2+ and the effector H+ in the pH range 5-6.6. The enzyme was activated by 100 mM-K+ and 32 mM-NH4+ throughout. It was found that the data could be described by the exponential model for a regulatory enzyme. On that basis, it was concluded that the binding of H+ is positively interactive and that the protonated enzyme is catalytically inactive. It was also found that H+ interacts positively with phosphoenolpyruvate but negatively with both ADP and Mg2+.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008956:Models, Chemical; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D011770:Pyruvate Kinase / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D011770:Pyruvate Kinase; D008274:Magnesium