Hexokinase - Worthington Enzyme Manual | Worthington Biochemical

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Hexokinase catalyzes the reaction:

Hexokinases have been isolated from the yeast cell in two distinct forms, designated P-I and P-II (Schulze et al. 1969). These are separate, noninterconvertible isozymes (Womack et al. 1973).

Hexokinase is used to determine glucose, fructose, mannose and ATP.

Characteristics of Hexokinase from Yeast:

Specificity

The enzyme phosphorylates D-fructose, 5-keto-D-fructose (Avigrad et al. 1968), D-glucose, 2-deoxy-D-glucose, D-mannose and D-glucosamine. ATP and ITP have been demonstrated to transphosphorylate in the yeast hexokinase reaction (Martinez 1961). The activity of P-I with fructose is 2.6 times that with glucose, whereas with P-II, a fructose:glucose ratio of 1:3 is obtained (Lazarus et al. 1966). The substrate specificities of yeast hexokinase have been extensively studied by Bessell et al. (1972).

Composition

Both P-I and P-II contain the same amino terminus, valine, and the same carboxy terminus, alanine. Amino acid composition has been reported by Schmidt et al. (1973b).

Characteristics of Hexokinase

Molecular Weight

The native forms have molecular weights of about 100,000 (Schulze et al. 1969) and consist of polypeptide chains of molecular weights slightly higher than 50,000 (Schmidt et al. 1973).

Optimal pH

7.5 - 9.0 (Sols et al. 1958).

Isoelectric point

P-I, 5.25 and P-II, 4.93 (Schmidt et al. 1973).

Extinction Coefficient

= 8.85 for P-I and 9.47 for P-II (Schmidt et al. 1973).

Activators

Hexokinase requires magnesium ions for its catalytic activity. It is activated by catecholamines and related compounds (Harrison et al. 1972). Calcium ions do not affect the enzymatic activity.

Inhibitors

The enzyme is inhibited by compounds which react with SH groups. It is also inhibited by sorbose-1-phosphate, polyphosphates, 6-deoxy-6-fluoroglucose, 2-C-hydroxy-methylglucose, xylose and lyxose (Sols et al. 1958 and McDonald 1955).

Stability

Both the lyophilized preparation and the crystalline suspension are stable for 6-12 months at 2-8°C.

Hexokinase Products

Description

Hexokinase, Lyophilized, Recomb

Source:

Recombinant Hexokinase from Yeast

A lyophilized powder. Phosphohexose isomerase, 6-phosphogluconate dehydrogenase, adenylate kinase and creatine phosphokinase contaminant activities are 0.10%, 0.005%, 0.005% and 0.005%, respectively.

Store at -20°C.

…

Activity

≥150 units per mg protein

Certificate of Analysis

Code

HKQLR

Product details

LS002515

2.5 ku

$66.00

LS002516

10 ku

$220.00

LS002518

Bulk

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Description

Hexokinase, Lyophilized

Source:

Yeast

Chromatographically purified. A lyophilized powder containing ~30% buffer/stabilizer. Phosphohexose isomerase, 6-phosphogluconate dehydrogenase, adenylate kinase and creatine phosphokinase contaminant activities are 0.10%, 0.005%, 0.005% and 0.005%, respectively.

Store at -20°C.

…

Activity

≥150 units per mg protein

Certificate of Analysis

Code

HKQL

Product details

Minimum order quantity

200000

LS002514

Bulk

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Description

Hexokinase, Suspension

Source:

Yeast

Chromatographically purified. A suspension in 2.8M ammonium sulfate. Phosphohexose isomerase, 6-phosphogluconate dehydrogenase, adenylate kinase and creatine phosphokinase contaminant activities are 0.05%, 0.003%, 0.005% and 0.005%, respectively.

Store at 2-8°C.

…

Activity

≥150 units per mg protein

Certificate of Analysis

Code

HKQS

Product details

Minimum order quantity

200000

LS002500

Bulk

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Please enter catalog number and quantity

Hexokinase - Manual

Hexokinase Products