Hexokinase - Manual

Source:
Yeast
CAS:
9001-51-8
EC:
2.7.1.1

Hexokinase catalyzes the reaction:

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

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
Activity
Code
Cat. #
Size
Price
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
Code
HKQLR
LS002515
2.5 ku
$66.00
LS002516
10 ku
$220.00
LS002518
Bulk
---
The minimum amount for bulk packaging/pricing for this product is 200 x 1 ku. Please contact custservice@worthington-biochem.com to request a quote for smaller amounts.
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
Code
HKQL
Minimum order quantity
200000
LS002514
Bulk
---
The minimum amount for bulk packaging/pricing for this product is 200000 x 1 ku. Please contact custservice@worthington-biochem.com to request a quote for smaller amounts.
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
Code
HKQS
Minimum order quantity
200000
LS002500
Bulk
---
The minimum amount for bulk packaging/pricing for this product is 200000 x 1 ku. Please contact custservice@worthington-biochem.com to request a quote for smaller amounts.