Unexpected lability of cysteine acetamidomethyl thiol protecting group. Tyrosine ring alkylation and disulfide bond formation upon acidolysis.
J Pept Res
; 49(4): 341-6, 1997 Apr.
Article
en En
| MEDLINE
| ID: mdl-9176818
Cleavage and deprotection of the peptidyl resin H-Asn-Gly-Gly-Cys (Acm)-Glu(OBu(t))-Gln-Tyr(Bu(t))-Cys(Acm)-Ser(Bu(t))-Asp( OBU(t))-[(p-alkoxy)benzyloxy polystyrene resin] using standard conditions with various trifluoroacetic acid-containing mixtures were found to result in partial removal of ordinarily acid-stable S-Acm groups. Thus, apart from the desired peptide H-Asn-Gly-Gly-Cys (Acm)-Glu-Gln-Tyr-Cys(Acm)-Ser-Asp-OH, a disulfide-cyclic peptide derivative was also isolated. Furthermore, it was found that in another major by-product of the peptide resin cleavage the tyrosine side chain had been alkylated with an Acm group in a position ortho to the phenolic function. The formation of both by-products could be suppressed by carrying out the cleavage/deprotection reaction at higher dilution and by inclusion of scavengers such as phenol. An authentic sample of the disulfide-cyclic peptide was obtained by oxidation of H-Asn-Gly-Gly-Cys-Glu-Gln-Tyr-Cys-Ser-Asp-OH using Ellman's reagent.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oligopéptidos
/
Péptidos Cíclicos
/
Resinas de Plantas
/
Compuestos de Sulfhidrilo
/
Tirosina
/
Cisteína
/
Disulfuros
Idioma:
En
Revista:
J Pept Res
Asunto de la revista:
BIOQUIMICA
Año:
1997
Tipo del documento:
Article
País de afiliación:
Noruega
Pais de publicación:
Dinamarca