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. Author manuscript; available in PMC: 2011 Mar 1.
Published in final edited form as: J Am Soc Mass Spectrom. 2009 Oct 29;21(3):323–337. doi: 10.1016/j.jasms.2009.10.013

Figure 1.

Figure 1

Higher order structure (top) and amino acid sequence (bottom) of IFN with elements of secondary structure labeled according to a commonly accepted nomenclature (44). Colored residues are common targets of non-enzymatic or designer PTMs: orange, Cys-17 (alkylation, oxidation, formation of external disulfides, internal disulfide scrambling, replacement with Ser in interferon β1b, PEGylation via thiol-reactive group); yellow, Cys-31 and Cys-141 (disulfide scrambling); cyan, Lys-19 (glycation (86)); magenta, methionine residues (oxidation); and green, Asn-90 (variable glycosylation and deglycosylation).