MASS-SPECTROMETRIC CHARACTERIZATION OF BOVINE CHROMAFFIN GRANULE PEPTIDES RELATED TO CHROMOGRANIN-B

Peptides were extracted from the lysate of isolated bovine chromaffin granules. Following reversed-phase HPLC purification, the fractions were analyzed by FAB/MS. The presence of methionine-enkephalin and leucine-enkephalin was indicated by their chromatographic retention time and by the m/z value of their protonated molecules. As to five new peptides related to chromogranin B, prominent protonated molecules were observed at m/z 1746, 1446, 1333, 977 and 901. Trypsinolysis resulted in a common loss of a component with mass 545, pointing to a structural relationship and a common precursor molecule. The peptide showing a (M + H)+ ion at m/z 1746 could be identified as a novel, recently reported, neuropeptide derived from chromogranin B, whereas the other peptides with (M + H)+ ions at m/z 1446. 1333, 977 and 901 could be characterized as smaller fragments of this peptide. Peptidase-guided sequence analysis and MS/MS analysis provided sequence information.