Studies on the active site of yeast hexokinase. Specific phosphorylation of a serine residue induced by D-xylose and ATPMg.
Yeast hexokinase A(ATP:D-hexose 6-phosphotransferase) is inactivated when incubated in the presence of xylose and ATPMg, or in the presence of D-lyxose in a reaction medium in which ATPMg is being continuously regenerated (phosphoenolpyruvate and pyruvate kinase). The inactivation is due to the phorphorylation of the protein. A linear relationship was observed between the inactivation and the incorporation of 32P from [gamma-32P] ATP. All hexokinase and ATPase activity of the enzyme is lost when one phosphoryl group is incorporated per enzyme subunit (molecular weight 51,000). The phosphoryl group is covalently bound by a ester linkage with a serine residue of the protein.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D001665:Binding Sites; D006593:Hexokinase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012694:Serine / Q000032:analysis; D014994:Xylose / Q000494:pharmacology*
D012694:Serine; D000255:Adenosine Triphosphate; D014994:Xylose; D006593:Hexokinase; D008274:Magnesium