40] Acyl phosphatase from skeletal muscle: Acetyl phosphate → acetate + orthophosphate

Abstract

Publisher Summary This chapter describes the preparation and purification of acyl phosphatase from skeletal muscle. The assay of acyl phosphatase utilizes acetyl phosphate as the substrate because of its common availability and adequate stability. The method is based on following the hydrolysis of acetyl phosphate by the hydroxamic acid method for measuring the residual substrate. It is found that because of the high dissociation constant for acyl phosphatase and acetyl phosphate, the level of substrate used is somewhat below the concentration needed to saturate the enzyme for a long period of time. The enzyme catalyzes the hydrolyses of acetyl, butyryl, and palmityl phosphate, 1,3-diphosphoglyceric acid, and carbamyl phosphate. The enzyme seems not to require a metal for activity as determined both by lack of effect of added metal ions and metal-binding inhibitors. The enzyme in liver differs from that of the muscle enzyme. It is not acid-heat stable, and it is not inhibited by inorganic phosphate. It is observed that in both these tissues the enzymes are largely present in the so-called soluble portion of the cell.