Post-translational processing of proteins generates structural and functional diversity. Many examples of post-translational modifications have been described in the literature. Of those described, proteolytic processing of precursor proteins remains a dramatic case of post- translational modification. This processing generates a vast array of peptides, growth factors, and hormones which serve as important intercellular messengers. One particular pathway of proteolytic processing is that one that leads to the generation of alpha-carboxamidated peptides. Our efforts have been directed to developing chemical assays for the alpha- carboxamidated peptides and their immediate precursors, the glycine- extended forms of the peptide. Employing thiohydatoin derivatives of these peptides, two assays have been developed which detect aminoacyl-alpha- carboxamides and carboxy-terminal glycine. These assays have been employed in screening tissue extracts of neuroendocrine tissues, known to be rich sources of alpha-carboxamidated and glycine-extended peptides.
