The enzymic activity of egg-white. Its bearing on the problem of watery-whites

Abstract

1. The enzymic activity of solutions of thick and thin albumen from normal and watery-white eggs has been studied, using a micro-titration method determining peptide cleavage in terms of the increase in amino nitrogen. 2. Thick or thin albumen alone at pH values ranging from 5.5 to 8.5 suffer no autolysis at 37°, neither can any protein-splitting enzyme be detected at any pH by the addition of gelatin as substrate. 3. The work of Balls and Swenson is criticised on account of insufficient sensitivity of the method employed and the fact that it is such as would fail to distinguish between an increase in acid groups due to lipolytic and due to proteolytic activity. Moreover, the use of casein as a substrate is incapable of differentiating protease from ereptase activity. 4. The presence in egg white of at least two erepsin-like enzymes having different pH optima (approximately 5.5 and 7.0-8.0) has been demonstrated. Whether or not these enzymes play any part in the development of “watery-white” is uncertain but for reasons discussed it would seem unlikely. Some observations upon “watery-white” in eggs are recorded and the problem subjected to a short discussion.