title: A synthetic glucagon-like peptide-1 analog with improved plasma stability.
abstract: Glucagon-like peptide-1 (GLP-1) is the most potent endogenous insulin-stimulating hormone. In the present study the plasma stability and biological activity of a GLP-1 analog, [Ser]GLP-1(7-36)amide, in which the second N-terminal amino acid alanine was replaced by serine, was evaluated in vitro and in vivo. Incubation of GLP-1 with human or rat plasma resulted in degradation of native GLP-1(7-36)amide to GLP-1(9-36)amide, while [Ser]GLP-1(7-36)amide was not significantly degraded by plasma enzymes. Using glucose-responsive HIT-T15 cells, [Ser]GLP-1(7-36)amide showed strong insulinotropic activity, which was inhibited by the specific GLP-1 receptor antagonist exendin-4(9-39)amide. Simultaneous i.v. injection of [Ser]GLP-1(7-36)amide and glucose in rats induced a twofold higher increase in plasma insulin levels than unmodified GLP-1(7-36)amide with glucose and a fivefold higher increase than glucose alone. [Ser]GLP-1(7-36)amide induced a 1.5-fold higher increase in plasma insulin than GLP-1(7-36)amide when given 1 h before i.v. application of glucose. The insulinotropic effect of [Ser]GLP-1(7-36)amide was suppressed by i.v. application of exendin-4(9-39)amide. The present data demonstrate that replacement of the second N-terminal amino acid alanine by serine improves the plasma stability of GLP-1(7-36)amide. The insulinotropic action in vitro and in vivo was not impaired significantly by this modification.
authors.affiliation: Department of Medicine, Division of Gastroenterology and Endocrinology, University of Göttingen, Göttingen, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Ritzel
authors.forename: U
authors.initials: U
authors.lastname: Leonhardt
authors.forename: M
authors.initials: M
authors.lastname: Ottleben
authors.forename: A
authors.initials: A
authors.lastname: Rühmann
authors.forename: K
authors.initials: K
authors.lastname: Eckart
authors.forename: J
authors.initials: J
authors.lastname: Spiess
authors.forename: G
authors.initials: G
authors.lastname: Ramadori
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005934:Glucagon / Q000378:metabolism*; D052216:Glucagon-Like Peptide 1; D000067757:Glucagon-Like Peptide-1 Receptor; D004763:Glucagon-Like Peptides; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018027:Receptors, Glucagon / Q000187:drug effects; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: C000593833:GLP1R protein, human; C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D018027:Receptors, Glucagon; C116749:glucagon-like peptide 1 (7-36)amide, Ser(8)-; C055453:glucagon-like peptide 1 (7-36)amide; C083773:exendin (9-39); D004763:Glucagon-Like Peptides; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose