THE PRIMARY STRUCTURE OF PANCREATIC-POLYPEPTIDE FROM A PRIMITIVE INSECTIVOROUS MAMMAL, THE EUROPEAN HEDGEHOG (ERINACEOUS-EUROPAEUS)

Pancreatic polypeptide (PP) has been isolated from extracts of the pan creas of the European hedgehog (Erinaceous europaeus) which is a repre sentative of the order Insectivora, deemed to be the most primitive gr oup of placental mammals. Pancreatic tissues were extracted in acidifi ed ethanol and the peptide was purified chromatographically using a PP C-terminal hexapeptide amide specific radioimmunoassay to monitor pur ification. Two major PP-immunoreactive peptides were baseline-resolved following the final analytical reverse phase HPLC fractionation. Each was separately subjected to plasma desorption mass spectroscopy (PDMS ) and gas-phase sequencing. The molecular masses of each peptide were similar: (I) 4237.6 +/- 4 Da and (II) 4238.2 +/- 4 Da. The full primar y structures of each peptide were deduced and these were identical: VP LEPVYPGDNATPEQMAHYAAELRRYINMLTRPRY. The peptides were deemed to be ami dated due to their full molar cross-reactivity with the amide-requirin g PP antiserum employed in radioimmunoassay. The molecular mass (4233. 8 Da) calculated from the sequence was in close agreemeent with PDMS e stimates and the reason for the different retention times of each pept ide is unknown at present. Hedgehog PP exhibits only 2 unique amino ac id substitutions, at positions 1 (Val) and 19 (His), when compared wit h other mammalian analogues.