Atlantic Cod Gastric Protease. Characterization with Casein and Milk Substrate and Influence of Sepharose Immobilization on Salt Activation, Temperature Characteristics and Milk Clotting Reaction

The temperature coefficient for the enzymic phase of milk clotting was lower for cod gastric protease than for calf rennet and various other rennet substitutes. Immobilization of cod pepsin on Sepharose resulted in an increase in Arrhenius activation energy for hemoglobin hydrolysis from 8.5 Kcal/mole to 12.8 Kcal/mole. Sepharose-cod protease did not catalyze the enzymic phase of milk clotting. Cold renneting of milk substrate with cod gastric protease at 0°C resulted in continued formation of nonprotein nitrogen (NPN) after the enzymic phase of milk clotting was complete. Initiation of milk clotting by raising the temperature to 39°C prevented the subsequent formation of NPN.