Krstenansky JL, Zechel C, Trivedi D, Hruby VJ. Importance of the C-terminal alpha-helical structure for glucagon's biological activity.
INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1988;
32:468-75. [PMID:
2854536 DOI:
10.1111/j.1399-3011.1988.tb01377.x]
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Abstract
The synthetic glucagon analogues [Glu21]glucagon, 2, and [Lys17,18,Glu21]glucagon, 3, were designed using Chou-Fasman calculations for the purpose of enhancing the probability for the formation of a C-terminal amphipathic alpha-helical conformation. Circular dichroism indicates increased alpha-helical content for these analogues in solution relative to glucagon. Analogues 2 and 3 also exhibit a 3-fold and 5-fold increase in receptor binding potency, respectively. The adenylate cyclase stimulating potencies of 2 and 3 relative to glucagon are 2.1 and 7 times greater, respectively. Attempts were made at further alpha-helical enhancement by further substitutions in the 10-13 region of glucagon, as represented by the glucagon analogues [Phe13,Lys17,18 Glu21]glucagon, 4, and [Phe10,13,Lys17,18,Glu21]glucagon, 5. These latter substitutions resulted in lowered receptor binding and adenylate cyclase potencies for 4 and 5 relative to 3 despite increased alpha-helical content in solution as observed by circular dichroism spectroscopy.
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