Intracellular proteolytic enzymes of liver

The influence of reaction upon autolysis of animal tissues has been exhaustively studied. All observers agree upon the favorable influence of a weak acid medium, and upon the inhibitory effect alkaline reaction. As an example of the influence of reaction upon autolysis, 2.5 grams of liver after five days at 37 degrees yield the following equivalents of ammonia by the Kjeldahl method; in 0.4 per cent. acetic acid, 35.6 cubic centimeters N/10 H₂SO₄; in 0.2 per cent. acetic acid, 34.8 cubic centimeters N/10 H₂SO₄; in neutral, 11.3 cubic centimeters N/10 H₂SO₄; in 0.2 per cent. sodium carbonate, 4.8 cubic centimeters N/10 H₂SO₄; and in 0.4 per cent. sodium carbonate, 0.6 cubic centimeter N/10 H₂SO₄.

When normal liver is allowed to stand on ice for many days, the power to digest in alkaline medium increases markedly from week to week until finally the enzyme solution is more active in alkaline than in acid medium. For instance, 2.5 grams of fresh liver after five days autolysis yields an equivalent in 0.2 per cent.