CGRP 27-37 analogues with high affinity to the CGRP1 receptor show antagonistic properties in a rat blood flow assay.
CGRP Y0-28-37 is known as a selective CGRP1 receptor antagonist. We succeeded in optimising the CGRP1 receptor affinity of this fragment by multiple amino acid replacement. The analogues [p34, F35]CGRP 27-37 and [D31, p34, F35]CGRP 27-37 exhibit a 100-fold increased affinity compared to the unmodified segment. Receptor binding studies were performed with human neuroblastoma cells SK-N-MC, which selectively express the hCGRP1 receptor. Blood flow, which is increased by exogenous CGRP, was measured in the right femoral artery. Preincubation of the rats with [p34, F35]CGRP 27-37 and [D31, p34, F35]CGRP 27-37 led to a significant decrease in CGRP induced increase in vascular conductance indicating the antagonistic properties of these compounds. Interestingly, an exchange of the amino acid Asn31 to Asp31 in [p34, F35]CGRP 27-37 shortened the period of the antagonistic effect significantly, suggestive of a different rate of metabolism for the two ligands. Secondary structure investigations obtained by circular dichroism measurements revealed that an increase in ordered structure correlates with high binding affinity.
Rist
B
B
Department of Pharmacy, ETH Zürich, Switzerland.
Lacroix
J S
JS
Entzeroth
M
M
Doods
H N
HN
Beck-Sickinger
A G
AG
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000031:analogs & derivatives*; D002942:Circular Dichroism; D005260:Female; D006801:Humans; D051381:Rats; D017208:Rats, Wistar; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism*
D018015:Receptors, Calcitonin Gene-Related Peptide; D015740:Calcitonin Gene-Related Peptide