title: Thio-alpha-amino acids (S-acids) as a carboxyl component in peptide synthesis catalysed by papain.
abstract: Peptide synthesis catalysed by papain was studied using thio-alpha-amino acids (S-acids) as a carboxyl component. It was found, for example, that with Z-AlaSH (pK 2.70) the maximal yield of the peptide Z-AlaValNH2 was obtained at pH 8-8.5. A two-fold excess of Z-AlaSH furnished peptides with yields close to 100%. Thio-amino acids with bulky side groups, for example, Z-IleSH, Z-Asp(OBu')SH, gave peptides with a low yield. Papain interacts with Z-AlaSH better than do bromelain or ficin.
authors.affiliation: Laboratory of Peptide Chemistry, Academy of Sciences of the USSR, Pushchino, Moscow Region.
authors.lastname: Mitin YuV
authors.forename: N P
authors.initials: NP
authors.lastname: Zapevalova
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002384:Catalysis; D008969:Molecular Sequence Data; D010206:Papain; D010455:Peptides / Q000138:chemical synthesis*; D013455:Sulfur
chemical_list: D000596:Amino Acids; D010455:Peptides; D013455:Sulfur; D010206:Papain