ISOLATION AND PRIMARY STRUCTURE OF A NOVEL AVIAN PANCREATIC-POLYPEPTIDE FROM 5 SPECIES OF EURASIAN CROW

Chicken pancreatic polypeptide is the prototype of the neuropeptide Y (NPY)/PP superfamily of regulatory peptides. This polypeptide was appe nded the descriptive term avian, despite the presence of some 8600 ext ant species of bird. Additional primary structures from other avian sp ecies, including turkey, goose and ostrich, would suggest that the pri mary structure of this polypeptide has been highly-conserved during av ian evolution. Avian pancreatic polypeptides structurally-characterise d to date have distinctive primary structural features unique to this vertebrate group including an N-terminal glycyl residue and a histidyl residue at position 34. The crow family, Corvidae, is representative of the order Passeriformes, generally regarded as the most evolutionar ily recent and diverse avian taxon. Pancreatic polypeptide has been is olated from pancreatic tissues from five representative Eurasian speci es (the magpie, Pica pica; the jay, Garrulus glandarius; the hooded cr ow, Corvus corone; the rook, Corvus frugilegus; the jackdaw, Corvus mo nedula) and subjected to structural analyses. Mass spectroscopy estima ted the molecular mass of each peptide as 4166 +/- 2 Da. The entire pr imary structures of 36 amino acid residue peptides were established in single gas-phase sequencing runs. The primary structures of pancreati c polypeptides from all species investigated were identical: APAQPAYPG DDAPVEDLLR-FYNDLQQYLNVVTRPRY. The peptides were deemed to be amidated due to their full molar cross-reactivity with the amide-requiring PP a ntiserum employed. The molecular mass (4165.6 Da), calculated from the sequences, was in close agreement with mass spectroscopy estimates. T he presence of an N-terminal alanyl residue and a prolyl residue at po sition 34 differentiates crow PP from counterparts in other avian spec ies. These residues are analogous to those found in most mammalian ana logues. These data suggest that the term avian, appended to the chicke n peptide, is no longer tenable due to the presence of an Ala1, Pro34 peptide in five species from the largest avian order. These data might also suggest that, in keeping with the known structure/activity requi rements of this peptide family, crow PP should interact identically to mammalian analogues on mammalian receptors.