title: Reaction mechanism of trypsin-catalysed semisynthesis of human insulin studied by fast atom bombardment mass spectrometry.
abstract: The production of semisynthetic human insulin for therapeutic purposes is of considerable importance. During trypsin-catalysed transformation of pig insulin into an ester of insulin of human sequence, the alanyl residue at position B30 is removed and replaced with an esterified residue of threonine. We have carried out this transformation in a medium enriched in 18OH2 and studied the product by MS. In contrast to a previous report, we find that incorporation of label into the B29 - B30 peptide bond occurs during the transformation with threonine methyl ester in aqueous N,N-dimethylacetamide. Quantitative data are presented and the implications of these findings are discussed.
authors.affiliation: Département de Biochimie Médicale, Centre Médical Universitaire, Geneva, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Rose
authors.forename: R
authors.initials: R
authors.lastname: Stöcklin
authors.forename: L A
authors.initials: LA
authors.lastname: Savoy
authors.forename: P O
authors.initials: PO
authors.lastname: Regamey
authors.forename: R E
authors.initials: RE
authors.lastname: Offord
authors.forename: P
authors.initials: P
authors.lastname: Vuagnat
authors.forename: J
authors.initials: J
authors.lastname: Markussen
mesh_terms: D000818:Animals; D002384:Catalysis; D006801:Humans; D007328:Insulin / Q000138:chemical synthesis*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013552:Swine; D014357:Trypsin / Q000378:metabolism*
chemical_list: D007328:Insulin; D014357:Trypsin