title: Sequencing of peptides and proteins with blocked N-terminal amino acids: N-acetylserine or N-acetylthreonine.
abstract: Many proteins cannot be directly sequenced by Edman degradation because they have a blocked N-terminal residue. A method is presented for deblocking such proteins when the N-terminal residue is N-acetylserine (which occurs frequently in eukaryotic proteins) or N-acetylthreonine. The method has been applied successfully to the determination of the N-terminal amino acid sequence of human, bovine, and rat parathymosins. Prothymosin alpha and other blocked proteins and peptides were also readily deblocked and sequenced by this procedure. It is proposed that the mechanism of the deblocking reaction involves an acid-catalyzed N----O shift of the acetyl group followed by a beta-elimination.
authors.affiliation: Department of Biochemistry, Cornell University Medical College, New York, NY 10021.
authors.forename: D
authors.initials: D
authors.lastname: Wellner
authors.forename: C
authors.initials: C
authors.lastname: Panneerselvam
authors.forename: B L
authors.initials: BL
authors.lastname: Horecker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D006801:Humans; D007202:Indicators and Reagents; D008722:Methods; D008969:Molecular Sequence Data; D010455:Peptides; D010669:Phenylthiohydantoin; D011506:Proteins; D051381:Rats; D012694:Serine / Q000031:analogs & derivatives*; D013912:Threonine / Q000031:analogs & derivatives*; D013947:Thymosin
chemical_list: D007202:Indicators and Reagents; D010455:Peptides; D011506:Proteins; C063269:N-acetylthreonine; D010669:Phenylthiohydantoin; D013912:Threonine; D012694:Serine; D013947:Thymosin; C012162:N-acetylserine