PRESENCE OF SOMATOSTATIN-28-(1-12) IN HYPOTHALAMUS AND PANCREAS

Acid extracts from rat pancreas and hypothalamus were analyzed for the presence of the antigenic determinant corresponding to the NH2 terminus of somatostatin-28 (SS28), using an antiserum directed against amino acids 1 to .ltoreq. 11 of the SS28 molecule. On gel permeation chromatography the majority of the immunoreactive material from each tissue extract eluted in 1 zone compatible with a peptide of 1250 daltons. Purification of this immunoreactive material by reverse-phase HPLC [high pressure liquid chromatography] and cation-exchange chromatography yielded 2 immunoreactive peptides from each tissue extract. The amino acid compositions of both peptides in pancreas and hypothalamus correspond to the fragment 1-12 of SS28. The more hydrophobic peptide from each tissue co-eluted with synthetic SS28-(1-12) on HPLC, while the other one coeluted with synthetic [Met(O)8]SS28-(1-12). Neither native peptide coeluted with synthetic SS28-(1-12)-amide. The prosomatostatin fragment Ser-Ala-Asn-Ser-Asn-Pro-Ala-Met-Ala-Pro-Arg-Glu-OH evidently is present in both rat hypothalamus and rat pancreas.