title: Synthesis of biologically active canine CCK-58.
abstract: The carboxyl terminal octapeptide of cholecystokinin (CCK-8) has been hypothesized to account for the bioactivity of all the molecular forms of cholecystokinin. However, the physiological relevance of CCK-58 has not been rigorously examined because of the lack of sufficient amounts of the peptide and concerns about inactivation of natural peptides during their purification. Therefore, canine-sulfated CCK-58 was synthesized and conditions determined for its unblocking and purification that preserved the sulfated tyrosine. Synthetic CCK-58 was indistinguishable from natural CCK-58 by amino acid analysis and by mass spectrometry. Synthetic CCK-58 and CCK-8 have different patterns of pancreatic stimulation: both caused a dose-related increase in amylase release, while only CCK-58 stimulated bile-pancreatic output volume. Thus, CCK-58 and CCK-8 are biased agonists at the CCK-A receptor (they have distinct patterns of action mediated by the same receptor). Previous work has demonstrated that the identical carboxyl termini of CCK-8 and CCK-58 have different solution conformations. Taken together, the physiological and structural results support the hypothesis that different carboxyl terminal conformations of CCK-58 and CCK-8 alter the expression of their biological activity.
authors.affiliation: CURE Digestive Diseases Research Center, VAGLAHS, Los Angeles, CA 90073, USA. jreeve@ucla.edu
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Reeve
authors.forename: David A
authors.initials: DA
authors.lastname: Keire
authors.forename: Tamer
authors.initials: T
authors.lastname: Coskun
authors.forename: Gary M
authors.initials: GM
authors.lastname: Green
authors.forename: Chris
authors.initials: C
authors.lastname: Evans
authors.forename: F J
authors.initials: FJ
authors.lastname: Ho
authors.forename: Terry D
authors.initials: TD
authors.lastname: Lee
authors.forename: Michael T
authors.initials: MT
authors.lastname: Davis
authors.forename: John E
authors.initials: JE
authors.lastname: Shively
authors.forename: Travis E
authors.initials: TE
authors.lastname: Solomon
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000681:Amylases / Q000378:metabolism; D000818:Animals; D002766:Cholecystokinin / Q000138:chemical synthesis* / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D013058:Mass Spectrometry / Q000379:methods; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; C410885:cholecystokinin 8; C038823:cholecystokinin 58; D002766:Cholecystokinin; D000681:Amylases