ABSTRACT
Protease-catalyzed oligomerization of natural or synthetic peptide monomers, not possessing classic plastein forming activity, was reported by Fruton and co-workers. The trypsin-mediated oligomerization of the tripeptide H-Ala-Ala-Arg-OH was described by Cerovsky and Jost. The major oligomerization products were free di- and tripeptides, whereas peptide esters were formed to a minor extent. Systematic studies of Virtanen, and Wieland, Determann, and co-workers, on the pepsin-induced assembly of synthetic peptides revealed that plasteins are products of protease-controlled oligomerization of suitable plastein-active peptide monomers. The chemical nature of the plasteins, which are usually formed as precipitates upon addition of proteases to concentrated peptic digests, was subject to considerable discussion for a long time. "Modified" plastein reactions have found practical applications in the chemistry of foods where they have been used to improve the nutritional quality of food proteins by incorporation of essential amino acids.
