Initial rate and isotope exchange studies of rat skeletal muscle hexokinase
The kinetic mechanism of rat skeletal muscle hexokinase (hexokinase II) was investigated in light of a proposal by Cornish-Bowden and his co-workers. The authors investigated the mechanism of action of hexokinase II by studying initial rate kinetics in the nonphysiological direction and by isotope exchange at chemical equilibrium. The former experiments were carried out in the absence of inhibitors and then with AMP, which is a competitive inhibitor of ADP, and with glucose 1,6-bisphosphate, a competitive inhibitor of glucose-6-P. The findings from these experiments suggest that the kinetic mechanism is rapid equilibrium Random Bi Bi. Isotope exchange at equilibrium studies also supports the random nature of the muscle hexokinase reaction; however, they also suggest that the mechanism is partially ordered, i.e. there is a preferred pathway associated with the branched mechanism. Approximately two-thirds of the flux through the hexokinase reaction involves the glucose on first glucose-6-P off last branch of the Random Bi Bi mechanism. These results imply that the kinetic mechanism is steady state Random Bi Bi. There is some evidence to suggest that glucose-6-P binds to an allosteric site on muscle hexokinase, but none to suppose that ATP binds allosterically.
- Research Organization:
- Iowa State Univ., Ames
- OSTI ID:
- 6259405
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HEXOKINASE
BIOCHEMISTRY
ISOTOPE DILUTION
MUSCLES
BIOCHEMICAL REACTION KINETICS
ATP
CARBON 14 COMPOUNDS
MATHEMATICS
RATS
ANIMALS
CHEMISTRY
ENZYMES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
NUCLEOTIDES
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
REACTION KINETICS
RODENTS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques