Studies on Brain Hexokinase

Kinetic studies of the brain hexokinase reaction.

The mechanism of the hexokinase reaction has been the subject of numerous investigations in recent years (l-5). ijgren and Engstrijm reported the incorporation of Pa from labeled adenosine triphosphate (ATP) into the phosphoserine moiety of hexokinase in the absence of substrate glucose and concluded that an enzyme-phosphate intermediate participated in the reaction (2). Gamble and Najjar, howe...

Studies on hexokinase. 1. The hexokinase activity of rat-brain extracts.

Studies on the kinetic mechanism and allosteric nature of bovine brain hexokinase.

Initial rate studies were carried out using solubilized bovine brain hexokinase. Both ATP 4and 0i, y-5'-adenylyl methylene diphosphonate are competitive inhibitors of MgATP 2and mixed inhibitors of the sugar substrate, while N-acetylglucosamine, a competitive inhibitor of fructose, is a mixed inhibitor of MgATP 2. These results are consistent with a random Bi Bi mechanism for the brain enzyme. ...

Kinetic studies of yeast hexokinase.

The mechanism of calf brain hexokinase has recently been studied in our laboratory (1). It was concluded from kinetic experiments that adenosine diphosphate (ADP) dissociates from the enzyme before addition of substrate glucose. This hypothesis was supported by kinetic studies of n-mannose, ADP, and glucose g-phosphate inhibition. The experiments appear to lend credence to theories in which an ...

Kinetic studies with skeletal-muscle hexokinase.

Rat skeletal-muscle hexokinase was partially purified by ammonium sulphate fractionation and gel filtration. The mechanism of the skeletal-muscle hexokinase was studied kinetically by initial-velocity analysis and product inhibition. Glucose 6-phosphate was a non-competitive inhibitor of glucose and ATP. ADP was a non-competitive inhibitor of glucose and a competitive inhibitor of ATP. The data...