Description
A hexokinase is an enzyme that phosphorylates hexoses (six-carbon sugars), forming hexose phosphate. In most organisms, glucose is the most important substrate of hexokinases, and glucose-6-phosphate the most important product. Hexokinase can transfer an inorganic phosphate group from ATP to a substrate. Hexokinases should not be confused with glucokinase, which is a specific isoform of hexokinase. While other hexokinases are capable of phosphorylating several hexoses, glucokinase acts with a 50-fold lower substrate affinity and its only hexose substrate is glucose.
Abbr
HK, chemically modified (Yeast)
Applications
Use Hexokinase in diagnostic tests for blood glucose using the hexokinase method and for the determination of creatine kinase.
Appearance
White lyophilizate
Product Overview
Recombinant enzyme that converts hexose to hexose-6-phosphate. Take advantage of the improved stability in liquid reagents. Rely on the proven diagnostic quality of this product.
Activity
> 40 U/mg lyophilizate
Contaminants
Alcohol dehydrogenase: <0.001 ATPase: <0.05 Creatine kinase: <0.001 G6P-DH: <0.005 Glutamate dehydrogenase: <0.05 Glutathione reductase: <0.005 Myokinase: <0.001 ''NADH oxidase'': <0.001 6-Phosphogluconate dehydrogenase: <0.001 Phophoglucose isomerase: <0.002 Phosphoglucomutase: <0.02 Glucose: <0.3 μg/mg lyophilizate
Molecular Weight
57 kD (SDS-PAGE)
Isoelectric point
4.5-5.0
Michaelis Constant
Phosphate buffer, 0.1 mol/l, pH 7.0; +25°C: 3.05 x 10-4 mol/l Phosphate buffer, 0.1 mol/l, pH 7.4; +30°C: 1.90 x 10-4 mol/l Tea buffer, 0.1 mol/l, pH 7.6; +25°C: 2.30 x 10-4 mol/l
Specificity
Hexokinase phosphorylates D-glucose, D-fructose, D-mannose, D-glucosamin, 2-deoxyglucose. L-Arabinose, D-xylose, L-rhamnose, D-galactose, D-lactose, sucrose, maltose, trehalose, raffinose, N-acetyl glucosamine do not react. ATP can be partially replaced by other nucleotides.
Activators
Mg2+, catecholamines
Stability
At +2 to +8°C within specification range for 18 months. Store dry.
Inhibitors
EDTA, SH-blocking compounds, sorbose-1-phosphate, polyphosphates, 6-deoxy-6-fluoroglucose, 2-C-hydroxymethylglucose, lyxose.
Synonyms
hexokinase type IV glucokinase; hexokinase D; hexokinase type IV; hexokinase (phosphorylating); ATP-dependent hexokinase; glucose ATP phosphotransferase; hexokinase; ATP:D-hexose 6-phosphotransferase