An overview of galanin’s actions on the endocrine pancreas

During studies to determine the primary structure of porcine cholecystokinin-pancreozymin (CCK), Mutt and Jorpes (1967) noted that the C-terminal dipeptide amide, aspartyl-phenylalanine amide, could be cleaved from the parent molecule and chromatographically separated from other peptide fragments. From this observation it was reasoned that the development of a general methodology to unequivocally identify and quantitate the individual C-terminal amide structures present in certain regulatory peptides, could provide the basis for an assay system for such regulatory peptides (Mutt, 1973). Tatemoto and Mutt (1978) devised a method whereby C-terminal alpha-amide structures are enzymatically cleaved from their parent biologically active peptides present in crude tissue extracts; following which, these liberated structures are chromatographically isolated, allowing precise identification of the amide structures and their quantitation. They demonstrated that their assay system could be used to follow the purification of known peptides from porcine intestinal extracts but, more importantly, they noted the presence in their tissue extracts of a number of C-terminal alpha-amide structures which could not have arisen from any regulatory peptide known at that time.