The effect of high pressures on pepsin and chymotrypsinogen.

A study of the inactivation of trypsin and chymotrypsin by high pressures was reported previously (1). The effects of high pressure on pepsin and chymotrypsinogen, and on the activation of chymotrypsinogen by trypsin, have now been examined. The effect of high pressure on crystalline pepsin was investigated by Matthews, Dow, and Anderson (2), in particular as affected by magnitude of pressure and duration of pressing. Most of their experiments were carried out at 35.5” and pH 4.8, at one concentration, and with pressing times of 1 to 8 hours. In the present investigation with pepsin, the effect of pH was studied in detail, and the effects of concentration, magnitude of pressure, pressing time, and multiple application of pressure were investigated in solutions in several buffers. The solutions were pressed at 25’ in all cases, and generally for only 5 minutes. Pepsin was found to be considerably more sensitive to pressure than was trypsin or chymotrypsin. It was most stable at pH 3.5 to 4.0. Under a given set of conditions, increasing the concentration of the pepsin generally resulted in a somewhat lower percentage loss of activity, whereas the reverse was true with trypsin. Increase in either pressure or pressing time resulted in further loss of activity of pepsin under all conditions tested; there was no tendency for the loss of activity to reach a maximum short of complete inactivation. Pressure did not activate chymotrypsinogen. As measured by subsequent activation by trypsin, chymotrypsinogen was found to be somewhat more stable under high pressures than was trypsin or chymotrypsin. The behavior was similar except that chymotrypsinogen was not significantly affected by multiple applications of pressure. A number of papers have been published on the effect of pressure on reactions catalyzed by enzymes (3-11). FrSinkel and Meldolesi (12) reported that the activity of pepsin, trypsin, and diastase was increased by pressures up to 10 atmospheres. Benthaus (13) found that the digestion