title: Further studies on the side reactions associated with use of N(pi)-benzyloxymethylhistidine.
abstract: The use of N(alpha)-tert.-butyloxycarbonyl-N(pi)-benzyloxymethylhistidine [Boc-His(Bom)] in peptide synthesis results in a serious level of side products arising from the generation of formaldehyde during the HF cleavage reaction. In particular, when treating a His(Bom)-containing peptide having Cys at the N-terminus by HF, this leads to almost complete conversion of the Cys-peptide to thiazolidyl (Thz)-peptide unless precautions are taken. Also, the reaction of formaldehyde with the N-terminal Trp and the N-methylanthranyl (Nma) group was found to produce tetrahydro-beta-carboline and dihydroquinazolin derivatives, respectively, upon isolation from HF mixtures. The addition of cysteine as a scavenger in HF proved to be effective for suppressing modification arising from the generation of formaldehyde.
authors.affiliation: Peptide Institute Inc., Protein Research Foundation, Minoh-shi, Osaka 562-8686, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yoshizawa-Kumagaye
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ishizu
authors.forename: Shuji
authors.initials: S
authors.lastname: Isaka
authors.forename: Masaji
authors.initials: M
authors.lastname: Tamura
authors.forename: Rumi
authors.initials: R
authors.lastname: Okihara
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishiuchi
authors.forename: Terutoshi
authors.initials: T
authors.lastname: Kimura
mesh_terms: D008762:Methylhistidines / Q000737:chemistry*; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D008762:Methylhistidines; C504366:N(pi)-benzyloxymethylhistidine; D010455:Peptides