TY - JOUR
T1 - Design and synthesis of conformationally constrained glucagon analogues
AU - Trivedi, Dev
AU - Lin, Ying
AU - Ahn, Jung Mo
AU - Siegel, Mara
AU - Mollova, Nevena N.
AU - Schram, Karl H.
AU - Hruby, Victor J.
PY - 2000
Y1 - 2000
N2 - Glucagon was systematically modified by forming lactam bridges within the central region of the molecule to give conformationally constrained cyclic analogues. Six cyclic glucagon analogues have been designed and synthesized. They are c[Asp9,Lys12][Lys17,18,Glu21]glucagon-NH2 (1), c[Asp9,Lys12]glucagon-NH2 (2), c[Lys12,Asp15]glucagon-NH2 (3), c[Asp15,Lys18]glucagon-NH2 (4), [Lys17-c[Lys18,Glu21]glucagon-NH2 (5), and c[Lys12,Asp21]glucagon-NH2 (6). The receptor binding potencies and receptor second messenger activities were determined by radio-receptor binding assays and adenylate cyclase assays, respectively, using rat liver plasma membranes. Most interestingly, analogues 1, 2, 3, and 4 were antagonists of glucagon stimulated adenylate cyclase activity, whereas analogues 5 and 6 were partial agonists in the functional assay. All of the cyclic analogues were found to have reduced binding potencies relative to glucagon. The structural features that might be responsible for these effects were studied using circular dichroism spectroscopy and molecular modeling. These results demonstrated the significant modulations of both receptor binding affinity and transduction (adenylate cyclase activity) that can accompany regional conformational constraints even in larger polypeptide ligands. These studies suggest that the entire molecular conformation, including the flexible middle portion, is important for molecular recognition and transduction at the hepatic glucagon receptor.
AB - Glucagon was systematically modified by forming lactam bridges within the central region of the molecule to give conformationally constrained cyclic analogues. Six cyclic glucagon analogues have been designed and synthesized. They are c[Asp9,Lys12][Lys17,18,Glu21]glucagon-NH2 (1), c[Asp9,Lys12]glucagon-NH2 (2), c[Lys12,Asp15]glucagon-NH2 (3), c[Asp15,Lys18]glucagon-NH2 (4), [Lys17-c[Lys18,Glu21]glucagon-NH2 (5), and c[Lys12,Asp21]glucagon-NH2 (6). The receptor binding potencies and receptor second messenger activities were determined by radio-receptor binding assays and adenylate cyclase assays, respectively, using rat liver plasma membranes. Most interestingly, analogues 1, 2, 3, and 4 were antagonists of glucagon stimulated adenylate cyclase activity, whereas analogues 5 and 6 were partial agonists in the functional assay. All of the cyclic analogues were found to have reduced binding potencies relative to glucagon. The structural features that might be responsible for these effects were studied using circular dichroism spectroscopy and molecular modeling. These results demonstrated the significant modulations of both receptor binding affinity and transduction (adenylate cyclase activity) that can accompany regional conformational constraints even in larger polypeptide ligands. These studies suggest that the entire molecular conformation, including the flexible middle portion, is important for molecular recognition and transduction at the hepatic glucagon receptor.
UR - http://www.scopus.com/inward/record.url?scp=0034108526&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034108526&partnerID=8YFLogxK
U2 - 10.1021/jm990559d
DO - 10.1021/jm990559d
M3 - Article
C2 - 10794689
AN - SCOPUS:0034108526
SN - 0022-2623
VL - 43
SP - 1714
EP - 1722
JO - Journal of Medicinal Chemistry
JF - Journal of Medicinal Chemistry
IS - 9
ER -