Enzymatic syntheses of N-protected Leu-enkephalin and some oligopeptides in organic solvents

DEPBT as an efficient coupling reagent for amide bond formation with remarkable resistance to racemization

3-(Diethoxyphosphoryloxy)-1, 2, 3-benzotriazin-4(3H)-one (DEPBT) is an effective coupling reagent for synthesis of linear and cyclic peptides by both solution and solid-phase peptide synthesis. DEPBT mediates amide bond formation with remarkable resistance to racemization. When DEPBT is used as a coupling reagent, it is not necessary to protect the hydroxy group of the amino component (such as tyrosine, serine, and threonine) and the imidazole group in the case of histidine. The high efficiency of DEPBT and its utility have been demonstrated in the syntheses of complex natural products such as ramoplanin A2, ramoplanose aglycon, ustiloxin, and teicoplanin aglycon.

Trypsin-catalysed synthesis of oligopeptide amides: comparison of catalytic efficiency among trypsins of different origin (bovine, Streptomyces griseus and chum salmon)

A procedure has been developed for the synthesis of oligopeptide amide using inverse substrates as acyl donors with amino acid amide instead of p-nitroanilide as acyl acceptor and trypsins of different origin (bovine, Streptomyces griseus and chum salmon trypsins) as the catalyst. The effectiveness of this procedure was demonstrated by the synthesis of a pentapeptide, Boc-[Leu5]-enkephalin amide, as a model compound. The method was the first enzymatic method shown to be successful at each successive coupling step for the synthesis of the oligopeptide. Bovine and chum salmon trypsins were superior to Streptomyces griseus trypsin as the catalyst.

Synthesis of N-protected peptide alcohols catalyzed by subtilisin or alpha-chymotrypsin in organic solvents

A series of N-protected peptide alcohols were synthesized using amino alcohols with unprotected hydroxy groups as amino components by the catalysis of subtilisin or alpha-chymotrypsin in organic solvents. N-protected aromatic amino acid esters were more suitable as acyl donors for subtilisin. The influences of different N-protecting groups, organic solvents, and content of water on synthesis of N-protected peptide alcohols were systematically studied.