Open AccessInhibition of Phosphoglycerate Kinase by Products and Product Homologues
Author(s) -
LarssonRaźnikiewicz Märtha,
Arvidsson Lars
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01570.x
Subject(s) - chemistry , enzyme , phosphoglycerate kinase , substrate (aquarium) , product inhibition , nucleotide , michaelis–menten kinetics , binding site , stereochemistry , non competitive inhibition , biochemistry , enzyme assay , biology , gene , ecology
This paper gives a presentation of ADP and AMP inhibition of phosphoglycerate kinase with MgATP 2− and 3‐phospho‐ d ‐glycerate as substrates at high and low Mg 2+ concentrations and pH 7.8. The enzyme seems to contain at least two nucleotide binding sites, one presumably binding to MgATP 2− and the other to ADP 3− . The ADP 3− binding site might bind MgADP 1− also. AMP 2− competes for the same form of the enzyme, probably the same site, as MgATP 2− . ADP 3− and MgADP 1− are competive inhibitors and AMP 2− is a non‐competitive inhibitor of 3‐ P ‐glycerate. Values of the inhibition constant, K i , for ADP 3− at low Mg 2+ level and MgADP 1− at high Mg 2+ level are 0.2 and 0.02 mM, respectively. The latter value is about ten times less than the expected Michaelis constant for corresponding substrate in the reverse reaction. K i for AMP is about 2.0 mM at both low and high Mg 2+ concentrations but the inhibition is stronger at a high than at a low Mg 2+ level, probably caused by conformational and/or other differences of the enzyme at these two metal ion concentrations. The main catalytic reaction suits a pattern that is consistent with a rapid equilibrium random mechanism.