Thermal stability of glucokinase (GK) as influenced by the substrate glucose, an allosteric glucokinase activator drug (GKA) and the osmolytes glycerol and urea.

ABSTRACT: We investigated how glycerol, urea, glucose and a GKA influence kinetics and stability of wild-type and mutant GK. Glycerol and glucose stabilized GK additively. Glycerol barely affected the TF spectra of all GKs but decreased k(cat), glucose S(0.5) and K(D) values and ATP K(M) while leaving cooperativity unchanged. Glycerol sensitized all GKs to GKA as shown by TF. Glucose increased TF of GKs without influence of glycerol on the effect. Glycerol and GKA affected kinetics and binding additively. The activation energies for thermal denaturation of GK were a function of glucose with K(D)s of 3 and 1mM without and with glycerol, respectively. High urea denatured wild type GK reversibly at 20 and 60°C and urea treatment of irreversibly heat denatured GK allowed refolding as demonstrated by TF

SUBMITTER: Zelent B 

PROVIDER: S-EPMC4180501 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature