Fragments of prosomatostatin isolated from a human pancreatic tumour.

Six peptides from an extract of a human pancreatic tumour were purified to homogeneity by HPLC. Amino acid composition and chemical properties indicated probable structures the same as somatostatin-14, somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-10), somatostatin-25 (1-9) and [Met(O)5]somatostatin-25 (1-9). The structure of somatostatin-14 was confirmed by sequence analysis. The isolation of these peptides provides insight into the processing of prosomatostatin in the tumour cells.