Amino acid substitutions in the sugar kinase/hsp70/actin superfamily conserved ATPase core of E. coli glycerol kinase modulate allosteric ligand affinity but do not alter allosteric coupling.

ABSTRACT: IIA(Glc), the glucose-specific phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system, is an allosteric inhibitor of Escherichia coli glycerol kinase. A linked-functions initial-velocity enzyme kinetics approach is used to define the MgATP-IIA(Glc) heterotropic allosteric interaction. The interaction is measured by the allosteric coupling constants Q and W, which describe the mutual effect of the ligands on binding affinity and the effect of the allosteric ligand on V(max), respectively. Allosteric interactions between these ligands display K-type activation and V-type inhibition. The allosteric coupling constant Q is about 3, showing cooperative coupling such that each ligand increases the affinity for binding of the other. The allosteric coupling constant W i

SUBMITTER: Pettigrew DW 

PROVIDER: S-EPMC2660850 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature