Isolation and Properties of Phospholipase a From Pollock Muscle

This study was undertaken to isolate and characterize phospholipase A from fish muscle tissue. The highest enzyme activity was present in the high speed supernatant of pollock muscle homogenate. This enzyme was purified 22‐fold by Sephadex G‐50 chromatography. The isolated enzyme preparation contained 9.2% nucleic acid: and 1.2% carbohydrate and had a molecular weight of approx. 13,700 daltons. Phospholipase A showed optimum activity between 37–42°C at a pH of 8.5–9.0. When dioctanoyl lecithin was used as the substrate an apparent Km value of 1.7 mM and a Vmax of 500 nmoles/min/mg protein were obtained in the presence of Ca ++ (4 mM). Calcium stimulated the enzyme whereas other divalent metal ions (Fe ++ , Mg ++ ) and ethylenediaminetetraacetic acid (EDTA) inhibited phospholipase activity.