title: The effect of pH on the interaction of substrates and effector to yeast and rabbit muscle pyruvate kinase.
abstract: The interaction of fructose 1,6-bisphosphate, phosphoenolpyruvate and ADP with pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) from yeast and rabbit muscle has been studied as a function of pH utilizing the quenching of protein fluorescence at 330 nm by these ligands. Both the muscle and the yeast pyruvate kinase interact with either ADP or phosphoenolpyruvate with similar affinity, indicating that the substrate-binding sites for these two isozymes are similar. The major difference between the yeast and muscle isozymes is their affinity with fructose 1,6-bisphosphate. Fructose 1,6-bisphosphate interacts with the yeast isozyme in orders of magnitude more strongly than with the muscle isozyme. Moreover, the affinity of fructose 1,6-bisphosphate to the yeast isozyme is strongly pH-dependent, while the interaction of fructose 1,6-bisphosphate with the muscle isozyme is independent of pH. The data indicate that yeast pyruvate kinase undergoes a conformational change as the pH is increased from 6.0 to 8.5.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D005635:Fructosediphosphates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D010728:Phosphoenolpyruvate / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011770:Pyruvate Kinase / Q000378:metabolism*; D011817:Rabbits; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
chemical_list: D005635:Fructosediphosphates; D007527:Isoenzymes; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; D010728:Phosphoenolpyruvate; D011770:Pyruvate Kinase; C029063:fructose-1,6-diphosphate