title: Peptide conjugation: unexpected ring opening of azacrown ether nucleophiles in the oxazolone-based coupling.
abstract: Unexpected cleavage of the macrocylic ring of secondary azacrown ethers when interacting with the Aib8 (Aib = alpha-aminoisobutyric acid) oxazolone indicates the possibility for a new mechanism of peptide racemization due to transformations of the oxazolones formed from the N-derivatives of alpha-amino acids in peptide synthesis.
authors.affiliation: Chemistry Department, Bar-Ilan University, Ramat-Gan 52900, Israel. belostot@mail.biu.ac.il
authors.forename: A M
authors.initials: AM
authors.lastname: Belostotskii
authors.forename: E
authors.initials: E
authors.lastname: Genizi
authors.forename: A
authors.initials: A
authors.lastname: Hassner
mesh_terms: D004986:Ether / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009943:Organophosphorus Compounds; D010080:Oxazoles / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013237:Stereoisomerism
chemical_list: D009943:Organophosphorus Compounds; D010080:Oxazoles; D010456:Peptides, Cyclic; D004986:Ether