Changes in the Activity of a Sarcoplasmic Adenosinetriphosphatase during Iced-storage and Frozen-storage of Cod

The changes in the activity of a sarcoplasmic ATPase during iced-storage and frozen-storage of cod, Gadus morhua, were examined in order to discuss whether the sarcoplasmic ATPase was useful as an index of quality test of iced-stored and frozen-stored cod or not. A few properties of this enzyme were studied too. A sarcoplasmic ATPase was present in an aqueous extract of cod flesh. This enzyme was activated by magnesium ion and inhibited by calcium ion and was believed to be attached to particulate matter which could be precipitated by centrifugation at 7, 000×g. When cod was stored in ice the activity was lost over 2 weeks but in only 1 week at -15°C. This enzyme is of potential value as an index of quality of iced but not frozen-stored cod.