Phosphoglucomutase

I.U.B.: 5.4.2.2

Enzymatic Reaction (image will open in a new window) 

Phosphoglucomutase (PGM) will interconvert the 1- and 6-phosphate isomers of a-D-glucose. Although it is a reversible reaction, the formation of glucose-6-phosphate is markedly favored. PGM will not convert β-D-glucose-1-phosphate or β-D-glucose-6-phosphate.

Characteristics of Phosphoglucomutase from Rabbit Muscle:

Molecular weight:

Approximately 62,000 daltons (Bergmeyer 1983).

Optimum pH:

7-5 - 8.0.

Activators:

Divalent cations, expecially Mg⁺⁺, glucose-1,6-bisphosphate and glutathione. Histidine, 8-hydroxyquinoline, and other metal-binding agents also stimulate the enzyme (Sutherland 1949).

Inhibitors:

High concentrations of chelating agents, gluconate-6-phosphate, nucleotides, and acetate.

Extinction coefficient:

= 7.70 (Najjar 1955).

Stability:

The enzyme is quite stable when dissolved in acetate buffer at pH 5.0. Its activity can be maintained for about 10 days at 2 - 8°C., then declines slowly over a period of 6 to 8 weeks. Najjar (1955) reports that below pH 4.5 and above pH 8.5 it is readily inactivated. In the crystalline state it is stable for months in 0.60 to 0.65 saturated ammonium sulfate containing 0.05 M acetate buffer, pH 5.0.