However , no alternative model had yet explained why proteins yield only amino acids and peptides upon hydrolysis and proteolysis .
Hence , alternative chemical models of proteins were considered , such as the diketopiperazine hypothesis of Emil Abderhalden .
No alternative model had yet explained why proteins yield only amino acids and peptides upon hydrolysis and proteolysis .
Hence , alternative chemical models of proteins were considered , such as the diketopiperazine hypothesis of Emil Abderhalden .