An Electrophoretic Investigation of the Degradation of alpha-Casein by Means of Pepsin and Trypsin.

Abstract

Pepsin and trypsin degrade [alpha]-casein in completely different ways. If this process (the tertiary phase) is followed by electrophoresis and by the increase of non-protein nitrogen (NPN), it is then found that pepsin and the previously studied rennin behave similarly in certain respects. Of these three enzymes rennin attacks the [alpha]-casein structure more specifically than pepsin and the latter in its turn more specifically than trypsin. The changes in the mobilities of the degradation products which can be observed during the process are different for different pH-values in the reaction mixture. In the pepsin investigations, the changes in the mobilities were proportional to the logarithm of the time. With trypsin, an electrophoresis pattern is obtained, after a few hours, which does not then change character throughout the rest of the experiment. The peaks decrease in height but they do not move or split up into several separate peaks. In the degradation experiments using pepsin, it was found that log NPN is proportional to log time. With trypsin, the process is however more complicated.