THE PROTEOLYTIC ACTIVITY OF THE CRUDE ENZYME EXTRACTS OF BALTIC COD (GADUS-MORHUA) ALIMENTARY-TRACT

The crude enzyme extract from Baltic cod alimentary tract had maximum activity of aspartic proteinases towards haemoglobin at pH 2.0 and 3.4 , and of serine proteinases with casein as the substrate at pH 8.3 and 10.4. With bovine myofibrils as the substrate the proteolysis at pH 5 .0-8.0 was maximum at the lowest and highest pH values. The optimum te mperature for the proteolytic activity at pH 3.4 and 10.4 was 30-45 de grees C and at pH 8.3 it was 40-50 degrees C. Heating the crude extrac t for 10 min at pH 3.4, 8.3, and 10.4 in the absence of the substrate had no effect on the activity of the acid and alkaline proteinases up to about 35-40 degrees C. The stability at higher temperature decrease d gradually and total inactivation occurred at 55-60 degrees C. In the pH range 5.5-7.5 the proteolytic activity against bovine myofibrils w as low at 0 degrees C but brought about significant loss of myosin hea vy chain at 20 degrees C.