Peptide structural analysis requires integration of several analytical techniques. The sequence of amino acids in a peptide may not be easily determined by DNA sequence analysis. Furthermore, post-transnational modification of the peptide may have occurred. Used along with amino acid analysis and sequential Edman degradation, mass spectrometric methods contribute additional information which helps to complete assignment of the structure. Using several chemical assays, including one developed for carboxy-terminal glycine and one recently developed to identify alpha- carboxamides, several putative neuropeptide precursors have been isolated from bovine pituitary and hypothalamus extracts. Several of these purified peptides have been identified as arising from proteolytic breakdown of myelin basic protein, actin and hemoglobin. Still screening and purifying peptides, we continue our search for novel neuropeptides that may arise by posttranslational processing of prohormone precursors.
