Properties of phosphoglucomutase from the ordinary muscle of pacific mackerel

Two phosphoglucomutases, MK (a) and MK (b), were partly purified from the ordinary (white) muscle of Pacific mackerel, Scomber japonicus, by ammonium sulfate fractionation, ion-exchange chromatography on a CM-Toyopearl column, and Sephacryl S-200 gel filtration. The enzymatic properties of the two enzymes were similar. Both had highest activity in 50 mM Tris-maleate buffer at pH 7.2 and in 50 mM Tris-HCl buffer at pH 8.0. The K_m value for glucose 1-phosphate was 1.0 ×10^ M for both. Activity was inhibited by 3-phosphoglycerate, adenosine monophosphate, and fructose 1,6-bisphosphate, which last caused the most inhibition and was non-competitive with glucose 1-phosphate. In the presence of 50 mM SO^_4, the enzyme had 10 to 27% the activity of the control; the activity was stimulated by 40 to 50% in the presence of 10 mM imidazole. These properties of phosphoglucomutases from Pacific mackerel were comparable to those of a rabbit muscle enzyme.記事区分：原