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Identification of oxidation sites and covalent cross-links in metal catalyzed oxidized interferon beta-1a: potential implications for protein aggregation and immunogenicity
Torosantucci, Riccardo Sharov, Victor S. van Beers, Miranda Brinks, Vera Schöneich, Christian Jiskoot, Wim
Torosantucci, Riccardo
Sharov, Victor S.
van Beers, Miranda
Brinks, Vera
Schöneich, Christian
Jiskoot, Wim
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Abstract
Oxidation via Cu2+/ascorbate of recombinant human interferon beta-1a (IFNβ1a) 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 IFNβ1a, formed via Cu2+/ascorbate catalyzed oxidation. Size exclusion chromatography (SEC) was used to confirm extensive aggregation of oxidized IFNβ1a. 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 crosslinks 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 IFNβ1a induced by oxidation, which have previously been shown to be highly immunogenic.
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2013-06-03
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American Chemical Society
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Torosantucci_2013.pdf
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IFNβ1a, Metal catalyzed oxidation, Covalent aggregation, Tyrosine oxidation products, Immunogenicity, Cu2+/ascorbate
Citation
Torosantucci, R., Sharov, V. S., van Beers, M., Brinks, V., Schöneich, C., & Jiskoot, W. (2013). Identification of oxidation sites and covalent cross-links in metal catalyzed oxidized interferon beta-1a: potential implications for protein aggregation and immunogenicity. Molecular Pharmaceutics, 10(6), 2311–2322. http://doi.org/10.1021/mp300665u