title: The C-terminal extension of exendin-4 provides additional metabolic stability when added to GLP-1, while there is minimal effect of truncating exendin-4 in anaesthetized pigs.
abstract: The most striking sequence difference between glucagon-like peptide-1 (GLP-1)(2) and the longer-acting GLP-1 receptor agonist, exendin-4 (Ex-4),(3) is the nine-amino acid COOH-terminal extension of Ex-4. We investigated the contribution of this extension to the survival time of Ex-4. We assessed the overall metabolism of GLP-1, Ex-4, a COOH-terminally extended GLP-1 peptide (GLP-1+Ex(31-39); GLP-Ex),(4) and a COOH-terminally truncated exendin peptide (Ex(1-30)) in anaesthetized, catheterized pigs, with focus on the extraction across the kidneys and a peripheral tissue (a hindleg, representing muscle, adipose- and connective tissue). Peptide analysis was carried out with assays against the mid-region of the peptides, whereby the role of dipeptidyl peptidase-4 (DPP-4)(5) mediated NH(2)-terminal degradation could be disregarded. The half-life of GLP-1 was significantly increased when the COOH-terminal extension of Ex-4 was added (GLP-1 4.8±3.3min; GLP-Ex 19.5±3.3min). In contrast, there was no effect of truncating Ex-4 (Ex-4 32.4±4.1min; Ex(1-30) 28.4±1.7min). Ex-4 and Ex(1-30) were cleared solely by the kidneys at rates corresponding to the glomerular filtration rate (GFR),(6) while GLP-1 and GLP-Ex were cleared by both the kidneys and peripheral tissues. Both extraction rates were, however, significantly reduced with GLP-Ex compared to GLP-1. The renal clearance rate of GLP-1 greatly exceeded GFR, while GLP-Ex was cleared at a rate resembling GFR. In conclusion, the COOH-terminal extension of Ex-4 contributes minimally to the increased survival time of Ex-4, while addition of this sequence to GLP-1 significantly reduces its clearance.
authors: University of Copenhagen, Department of Biomedical Sciences, Panum Institute, Blegdamsvej 3, 2200 Copenhagen N, Denmark.
authors: L
authors: L
authors: Simonsen
authors: J J
authors: JJ
authors: Holst
authors: K
authors: K
authors: Madsen
authors: C F
authors: CF
authors: Deacon
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D000758:Anesthesia; D000818:Animals; D018819:Dipeptidyl Peptidase 4 / Q000097:blood; D000077270:Exenatide; D005260:Female; D005919:Glomerular Filtration Rate; D052216:Glucagon-Like Peptide 1 / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D006207:Half-Life; D007004:Hypoglycemic Agents / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D008116:Lizards; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D010455:Peptides / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D055550:Protein Stability; D059748:Proteolysis; D013329:Structure-Activity Relationship; D013552:Swine; D014688:Venoms / Q000097:blood* / Q000138:chemical synthesis / Q000493:pharmacokinetics
chemical_list: D029845:Amphibian Proteins; D007004:Hypoglycemic Agents; D010446:Peptide Fragments; D010455:Peptides; D014688:Venoms; D052216:Glucagon-Like Peptide 1; D000077270:Exenatide; D018819:Dipeptidyl Peptidase 4