PHOSPHOGLUCOMUTASE, PHOSPHORIBOMUTASE, AND PHOSPHOGLUCOISOMERASE OF LINGCOD MUSCLE

Abstract

Aqueous extracts of lingcod muscle were saturated with ammonium sulphate and the resulting protein fraction was dialyzed to yield a crude preparation which exhibited marked PGM,* PRM, and PGI activities. When such preparations were flash heated to 55 °C and lyophilized, the remaining soluble-protein fraction could be chromatographed on DEAE cellulose columns using gradient elution with tris buffers to separate the PGI from the PGM and PRM activities which were eluted simultaneously. The properties of the pooled PGI fraction thus obtained were similar to those described in the literature from PGI prepared from widely different sources. Instability of the pooled fraction containing PGM and PRM made it difficult to employ this for studies of these enzyme activities, and therefore the crude ammonium sulphate fraction appropriately diluted was used. In this fraction PGM activity was at least 100 times that of PRM activity, and when in the dephospho form both PGM and PRM were inactive unless either GDP, RDP, or DROP was added. The action of Mg⁺⁺, CSH, and 8-hydroxyquinoline on PGM and PRM was studied with results which showed marked differences in response of the two enzymes to these agents.