RABBIT PANCREATIC-POLYPEPTIDE

1. In almost all studies involving localization or quantitation of reg ulatory peptides, an essential prerequisite is the generation of speci fic antisera in rabbits. Despite this almost universal practice, the p rimary structures of some established regulatory peptides, such as pan creatic polypeptide (PP), of the rabbit, remain unknown. 2. Here we re port the full primary structure of PP isolated from extracts of rabbit pancreas. 3. PP immunoreactivity was purified using an antiserum (PP 221) generated to the highly-conserved C-terminal hexapeptide amide of mammalian PP. A single molecular form of rabbit PP was consistently r esolved during sequential chromatographic fractionations. 4. Automated Edman degradation established the full primary structure as: APPEPVYP GDDATPE-QMAEYVADLRRYINMLTRPRY. The molecular mass derived from this se quence (4196.7 Da), was in full agreement with that determined by mass spectroscopy (4196 Da). The peptide was deemed to be C-terminally ami dated due to its full molar crossreactivity with the amide-requiring P P antiserum employed. 5. When compared with all other known mammalian PP sequences, rabbit PP displays three unique substituted sites, Pro a t position 3, Glu at position 19 and Val at position 21