Serine-Protease-Assisted Synthesis of Peptide Substrates for α-Chymotrypsin

δ-Chymotraypsin catalyzes peptide-bond formation between acylated amino-acid and peptide esters as the carboxyl component and amino-acid and peptide amides as the amino component. The conditions under which enzyme-catalyzed coupling can be used for fragment condensation in peptide synthesis is investigated. To illustrate the method the synthesis of tetra-, penta- and hexapeptides of the structure Ac-Lxn … LxlLyl … LymNH2 with Lxl Tyr, designed as substrates for α-chymotrypsin, is described.