Isolation and characterization of proSS 1–32, a peptide derived from the N-terminal region of porcine preprosomatostatin

A peptide derived from the N-terminal region of porcine prosomatostatin, proSS 1–32, has been purified to homogeneity from extracts of porcine upper intestine. Amino acid analysis revealed that the peptide consists of 32 residues. The complete primary structure was determined as: A P S D P R L R Q F L Q K S L A A A A G K Q E L A K Y F L A E L This sequence obviously comprises residues 1–32 of porcine prosomatostatin since it is identical to the corresponding sequence in human preprosomatostatin. The postulated cleavage site in porcine prosomatostatin is a Leu-Leu bond between residues 32 and 33, thus confirming previous studies of the processing of the somatostatin precursor in the rat and transgenic mouse.