The Formation of Ammonia from Proteins in Alkaline Solution

Considerable amounts of ammonia may be formed during the alkaline hydrolysis of proteins. Osborne, Leavenworth, and Brautlecht (1) were of the opinion that the amide and guanidine groups of the protein were the sole source of this ammonia.” In the alkaline hydrolysis of wheat gliadin, however, Vickery (2) observed a slow formation of ammonia from unidentified sources. The significance of the observation was masked by the unusually large amount of amide nitrogen in this protein. In the report which follows, we present evidence that considerable amounts of ammonia may originate in groups other than amide and guanidine. A part of this may plausibly be attributed to partial deamination of cystine (3, 4), histidine (5), and serine (6). The evidence indicates, however, that a notable part-and that liberated under quite mild conditions of hydrolysis-originates in some structural feature of the protein itself, rather than in any specific amino acid component. The proteins studied were crystalline preparations of egg albumin, edestin, and fl-lactoglobulin.2