A new approach to search for the bioactive conformation of glucagon: Positional cyclization scanning

J. M. Ahn, P. M. Gitu, M. Medeiros, J. R. Swift, D. Trivedi, V. J. Hruby

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

In search for the bioactive conformation of glucagon, "positional cyclization scanning" was used to determine secondary structures of glucagon required for maximal interaction with the glucagon receptor. Because glucagon is flexible in nature, its bioactive conformation is not known except for an amphiphilic helical conformation at the C-terminal region. To understand the conformational requirement for the N-terminal region that appears to be essential for signal transduction, a series of glucagon analogues conformationally constrained by disulfide or lactam bridges have been designed and synthesized. The conformational restrictions via disulfide bridges between cysteine i and cysteine i + 5, or lactam bridges between lysine i and glutamic acid i + 4, were applied to induce and stabilize certain corresponding secondary structures. The results from the binding assays showed that all the cyclic analogues with disulfide bridges bound to the receptor with significantly reduced binding affinities compared to their linear counterparts. On the contrary, glucagon analogues containing lactam bridges, in particular, c[Lys5, Glu9]glucagon amide (10) and c[Lys17, Glu21]glucagon amide (14), demonstrated more than 7-fold increased receptor binding affinities than native glucagon. These results suggest that the bioactive conformation of glucagon may adopt a helical conformation at the N-terminal region as well as the C-terminal region, which was not evident from earlier biophysical studies of glucagon.

Original languageEnglish (US)
Pages (from-to)3109-3116
Number of pages8
JournalJournal of Medicinal Chemistry
Volume44
Issue number19
DOIs
StatePublished - Sep 13 2001

Fingerprint

Cyclization
Glucagon
Conformations
Scanning
Lactams
Disulfides
Amides
Cysteine
Glucagon Receptors
Signal transduction
Lysine
Glutamic Acid
Assays
Signal Transduction

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

A new approach to search for the bioactive conformation of glucagon : Positional cyclization scanning. / Ahn, J. M.; Gitu, P. M.; Medeiros, M.; Swift, J. R.; Trivedi, D.; Hruby, V. J.

In: Journal of Medicinal Chemistry, Vol. 44, No. 19, 13.09.2001, p. 3109-3116.

Research output: Contribution to journalArticle

Ahn, J. M. ; Gitu, P. M. ; Medeiros, M. ; Swift, J. R. ; Trivedi, D. ; Hruby, V. J. / A new approach to search for the bioactive conformation of glucagon : Positional cyclization scanning. In: Journal of Medicinal Chemistry. 2001 ; Vol. 44, No. 19. pp. 3109-3116.
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