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Kinetic Cooperativity in Human Pancreatic Glucokinase Originates from Millisecond Dynamics of the Small Domain
Author(s) -
Larion Mioara,
Hansen Alexandar L.,
Zhang Fengli,
BruschweilerLi Lei,
Tugarinov Vitali,
Miller Brian G.,
Brüschweiler Rafael
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201501204
Subject(s) - cooperativity , glucokinase , chemistry , intramolecular force , kinetic energy , conformational isomerism , cooperative binding , crystallography , biophysics , stereochemistry , enzyme , biochemistry , biology , organic chemistry , molecule , physics , quantum mechanics
The hallmark of glucokinase (GCK), which catalyzes the phosphorylation of glucose during glycolysis, is its kinetic cooperativity, whose understanding at atomic detail has remained open since its discovery over 40 years ago. Herein, by using kinetic CPMG NMR spectroscopic data for 17 isoleucine side chains distributed over all parts of GCK, we show that the origin of kinetic cooperativity is rooted in intramolecular protein dynamics. Residues of glucose‐free GCK located in the small domain displayed distinct exchange behavior involving multiple conformers that are substantially populated ( p >17 %) with a k ex value of 509±51 s −1 , whereas in the glucose‐bound form these exchange processes were quenched. This exchange behavior directly competes with the enzymatic turnover rate at physiological glucose concentrations, thereby generating the sigmoidal rate dependence that defines kinetic cooperativity.