Sequence sensitivity and pH dependence of maleimide conjugated N-terminal cysteine peptides to thiazine rearrangement.
J Pept Sci
; 27(7): e3323, 2021 Jul.
Article
en En
| MEDLINE
| ID: mdl-33786923
Thiazine formation during the conjugation of N-terminal cysteine peptides to maleimides is an underreported side reaction in the peptide literature. When the conjugation was performed at neutral and basic pH, we observed the thiazine isomer as a significant by-product. Nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of the six-membered thiazine and ultra-high performance liquid chromatography (UHPLC) combined with tandem mass spectrometry (MS/MS) allowed for facile, unambiguous detection due to a unique thiazine mass fragment. Furthermore, substitution of various amino acids adjacent to the N-terminal cysteine in a tripeptide model system resulted in different rates of thiazine formation, albeit within the same order of magnitude. We also determined that varying the N-substitution of the maleimide affects the thiazine conversion rate. Altogether, our findings suggest that thiazine rearrangement for N-terminal cysteine-maleimide adducts is a general side reaction that is applicable to other peptide or protein systems. Performing the conjugation reaction under acidic conditions or avoiding the use of an N-terminal cysteine with a free amino group prevents the formation of the thiazine impurity.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Péptidos
/
Tiazinas
/
Cisteína
/
Maleimidas
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Idioma:
En
Revista:
J Pept Sci
Asunto de la revista:
BIOQUIMICA
Año:
2021
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Reino Unido