Synthesis of biologically active canine CCK-58.
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.
Reeve
Joseph R
JR
CURE Digestive Diseases Research Center, VAGLAHS, Los Angeles, CA 90073, USA. jreeve@ucla.edu
Keire
David A
DA
Coskun
Tamer
T
Green
Gary M
GM
Evans
Chris
C
Ho
F J
FJ
Lee
Terry D
TD
Davis
Michael T
MT
Shively
John E
JE
Solomon
Travis E
TE
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
D000596:Amino Acids; D010446:Peptide Fragments; C410885:cholecystokinin 8; C038823:cholecystokinin 58; D002766:Cholecystokinin; D000681:Amylases