Proteolytic Activities in Alfalfa (Medicago sativa L.) Leaves

Autodigestion in alfalfa (Medicago sativa L. cv Messe) leaves takes place at a higher rate in the acidic range of pH suggesting that acid proteases are probably involved in protein breakdown. Several lines of evidence show that alfalfa leaves contain various proteolytic activities. A carboxypeptidase active on CBZ-Phe-Met and on other CBZ-dipeptides with a pH optimum of 5.5 has been partially purified by CM-cellulose chromatography. Another acid protease, probably endopeptidase, is active on hemoglobin with an optimum at pH 4.5; perhaps it is not a single protease since it shows another peak of activity at pH 7-7.5. In the neutral-alkaline range of pH there are at least three peptidases active on naphthylamides. One of these, active on Lys-NA, is most active in very young leaves and probably is aSH dependent protease.