A new mass-spectrometric C-terminal sequencing technique finds a similarity between gamma-interferon and alpha 2-interferon and identifies a proteolytically clipped gamma-interferon that retains full antiviral activity.
A novel mass-spectrometric technique is described that permits the identification of the C-terminal peptide of a protein. The technique involves the incorporation of 18O into all alpha-carboxy groups liberated during enzyme-catalysed partial hydrolysis of the protein, followed by mass spectrometry to identify as the C-terminal peptide the only peptide that did not incorporate any 18O. The technique has been used to identify the true C-terminal tryptic peptide of a bacterially produced gamma-interferon and to distinguish it from a peptide produced by anomalous tryptic cleavage. It was found that a closely similar sequence segment of bacterially produced alpha 2-interferon undergoes an analogous cleavage. The technique was also used to identify the C-terminus of a clipped gamma-interferon that retains full antiviral activity.
D000595:Amino Acid Sequence; D008401:Gas Chromatography-Mass Spectrometry; D007370:Interferon Type I; D007371:Interferon-gamma; D010103:Oxygen Isotopes; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
D007370:Interferon Type I; D010103:Oxygen Isotopes; D010446:Peptide Fragments; D007371:Interferon-gamma; D014357:Trypsin