Identification of oxidation sites and covalent cross-links in metal catalyzed oxidized interferon Beta-1a: potential implications for protein aggregation and immunogenicity.
Mol Pharm
; 10(6): 2311-22, 2013 Jun 03.
Article
in En
| MEDLINE
| ID: mdl-23534382
ABSTRACT
Oxidation via Cu(2+)/ascorbate of recombinant human interferon beta-1a (IFNß1a) leads to highly immunogenic aggregates, however it is unknown which amino acids are modified and how covalent aggregates are formed. In the present work we mapped oxidized and cross-linked amino acid residues in aggregated IFNß1a, formed via Cu(2+)/ascorbate catalyzed oxidation. Size exclusion chromatography (SEC) was used to confirm extensive aggregation of oxidized IFNß1a. Circular dichroism and intrinsic fluorescence spectroscopy indicated substantial loss of secondary and tertiary structure, respectively. Derivatization with 4-(aminomethyl)benzenesulfonic acid was used to demonstrate, by fluorescence in combination with SEC, the presence of tyrosine (Tyr) oxidation products. High performance liquid chromatography coupled to electrospray ionization mass spectrometry of reduced, alkylated, and digested protein was employed to localize chemical degradation products. Oxidation products of methionine, histidine, phenylalanine (Phe), tryptophan, and Tyr residues were identified throughout the primary sequence. Covalent cross-links via 1,4- or 1,6-type addition between primary amines and DOCH (2-amino-3-(3,4-dioxocyclohexa-1,5-dien-1-yl)propanoic acid, an oxidation product of Phe and Tyr) were detected. There was no evidence of disulfide bridge, Schiff base, or dityrosine formation. The chemical cross-links identified in this work are most likely responsible for the formation of covalent aggregates of IFNß1a induced by oxidation, which have previously been shown to be highly immunogenic.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Interferon-beta
Type of study:
Diagnostic_studies
Limits:
Humans
Language:
En
Journal:
Mol Pharm
Journal subject:
BIOLOGIA MOLECULAR
/
FARMACIA
/
FARMACOLOGIA
Year:
2013
Type:
Article
Affiliation country:
Netherlands