Affordable Access

Publisher Website

Structure-activity studies with somatostatin: role of lysine in positions 4 and 9 for gastric activity

Authors
Journal
Regulatory Peptides
0167-0115
Publisher
Elsevier
Publication Date
Volume
8
Issue
4
Identifiers
DOI: 10.1016/0167-0115(84)90035-1
Keywords
  • Gastric Acid Secretion
  • Peptides
  • Somatostatin
  • Structure-Activity Relationships

Abstract

Abstract The gastric inhibitory activity of somatostatin analogues modified in position 4 or 9, was investigated in conscious cats prepared with gastric fistulae. Gastric secretion was stimulated with pentagastrin. Deletion of Lys 4, or substitution with an alcoholic (Thr) or acidic (Glu) residue yielded analogues with reduced (10% or less) potency compared with somatostatin. In comparison, [Phe 4]somatostatin and modified Phe 4 analogues ([p-NH 2-Phe 4]-, [F 5Phe 4]- and [Phe 4, d-Trp 8]somatostatin) were approximately equipotent with somatostatin. The high potency of the Phe 4 analogues illustrates that a basic side-chain in position 4 is not essential for gastric activity. In contrast, [Thr 9]-, [Glu 9]-, [Phe 9]- and [p-NH 2-Phe 9]somatostatin were all inactive (< 5% potency of somatostatin) in the stomach. Thus the lysyl residue in position 9 is more critical than that in position 4 for somatostatin's gastric activity.

There are no comments yet on this publication. Be the first to share your thoughts.