Affinity Labeling by m‐Nitrobenzenediazonium Fluoroborate of Porcine Anti‐Dinitrophenyl Antibodies

Publisher Website
Google Scholar
Abstract
From the tryptic digest of γ‐chains of porcine anti‐dinitrophenyl antibody which has been affinity‐labeled by m‐nitrobenzenediazonium fluoroborate, an azotyrosine‐containing peptide consisting of 28 amino acid residues was isolated using affinity chromatography on Sepharose‐bound antibodies. The peptide contained a half‐cystine residue and a tryptophan residue, The thermolysin digest of this peptide yielded several shorter pep tides. The amino acid sequence in the vicinity of the half‐cystine was revealed by the finding of the peptide Leu‐Ser‐Cys(O3H). Azotyrosine was found in a nonapeptide, the amino acid sequence of which was characterized by the presence of more than one amino acid in most of the steps of sequential degradation.Comparison of the amino acid sequence in the vicinity of the half‐cystine residue and of the partial amino acid sequence of the azotyrosine‐containing nonapeptide with the known sequences of heavy chains of man, rabbit, mouse and guinea‐pig immunoglobulins showed that the labeled tyrosine of γ‐chains of porcine anti‐dinitrophenyl antibody is located most likely in the hyper‐variable section between half‐cystine 22 and tryptophan 36.