The squid hepatopancreas, containing 20-60% lipids, is not suitable on board vessel for producing fodder meal and is often discarded, although it constitutes the major part of the viscera and is a rich source of proteolytic enzymes. The proteolytic activity against hemoglobin at pH 3.0 of the extract of the he pato pan ere a s of frozen stored squid, calculated per mg of protein, is about 20 times higher than that of the extract of the rest of the viscera. Due to incubation of the homogenate at pH 3.0 at 30 and 40°C in 2 days a clear watery phase was formed, well separated from the oily fraction containing floating solid particles of the autolysate. In 2 days about 35 and 50% of the protein was hydrolysed at 20°C and 30-40°C, respectively, to degradation products not precipitated by TCA. The proteolytic activity of the autolyzed homogenate after 2 days at pH 3.0 is about 80 % of that of the original homogenate. Incubation at 40°C at pH 3.0 decreased the activity after 6 days by about 50%. In the autolysate of squid hepatopancreas the proteolytic activity at pH 3.0 in the absence of reducing compounds was almost totally due to aspartic proteases. In the presence of dithiothreitol the activity increased by about 50%, but the increase was only partly due to the presence of thiol proteases.
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