Structural characterization of fibroblast human interferon-beta 1.

The complete amino acid sequence of fibroblast human interferon-beta 1 (IFN-beta 1) was determined, and the higher-order structure of the protein was characterized with Raman spectroscopy. That amino acid sequence was identical to the entire sequence deduced from the cDNA nucleotide sequence, showing there are no proteolytic cleavages of carboxy-terminal residues in contrast to natural human IFN-alpha and natural human IFN-gamma. The N-glycosylation site was confirmed as Asn-80 by the detection of glucosamines in the peptide containing Asn-80. An S-carboxymethyl Cys-17 was detected in the S-carboxymethylated protein, suggesting that Cys-17 is unpaired. Raman spectra indicated a predominance of alpha-helical backbone and three Cys residues in this protein form, one unpaired Cys residue and one disulfide bond. These results provide some evidence for the primary and higher-order structures of natural IFN-beta 1 so far predicted.