Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon

The importance of charged residues and salt bridges in glucagon biological activity

Noel S. Sturm, Ying Lin, Stephen K. Burley, John L. Krstenansky, Jung Mo Ahn, Bassem Y. Azizeh, Dev Trivedi, Victor J Hruby

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We have designed and synthesized eight compounds 2-9 which incorporate various amino acid residues in positions 17, 18, and 21 of the glucagon molecule: 2, [Lys17]glucagon amide; 3, [Lys18]glucagon amide; 4, [Nle17,Lys18,Glu21]glucagon amide; 5, [Orn17,18 Glu21]glucagon amide; 6, [D-Arg17]glucagon; 7, [D-Arg18]glucagon; 8, [D- Phe17]glucagon; and 9, [D-Phe18]glucagon. Compared to glucagon (IC50 = 1.5 nM), analogues 2-9 were found to have binding affinity IC50 values (in nM) of 0.7, 4.1, 1.0, 2.0, 5.0, 25.0, 43.0, and 32.0, respectively. When these compounds were tested for their ability to stimulate adenylate cyclase (AC) activity, they were found to be full or partial agonists having maximum stimulation values of 100, 100, 100, 100, 87, 78, 94, and 100%, respectively. On the basis of the X-ray crystal structure of [Lys17,18,Glu21]glucagon amide reported here, the ability to form a salt bridge between Lys18 and Glu21 is probably key to their increased binding and second messenger activities. Among the eight analogues synthesized here, only analogue 4 preserves the ability to form a salt bridge between Lys18 and Glu21. However, since these modifications are minor they do not seem to change the amphiphilic character of the C-terminus, allowing these analogues to reach 78-100% stimulation in the adenylate cyclase assay. Biological data from analogues 6-9 supports the idea that position 18 of glucagon may influence binding only, while position 17 may influence both receptor recognition and transduction.

Original languageEnglish (US)
Pages (from-to)2693-2700
Number of pages8
JournalJournal of Medicinal Chemistry
Volume41
Issue number15
DOIs
StatePublished - Jul 16 1998

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Bioactivity
Glucagon
Salts
Amides
Adenylyl Cyclases
Inhibitory Concentration 50
Second Messenger Systems
Assays
Crystal structure
X-Rays
Amino Acids
X rays

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon : The importance of charged residues and salt bridges in glucagon biological activity. / Sturm, Noel S.; Lin, Ying; Burley, Stephen K.; Krstenansky, John L.; Ahn, Jung Mo; Azizeh, Bassem Y.; Trivedi, Dev; Hruby, Victor J.

In: Journal of Medicinal Chemistry, Vol. 41, No. 15, 16.07.1998, p. 2693-2700.

Research output: Contribution to journalArticle

Sturm, Noel S. ; Lin, Ying ; Burley, Stephen K. ; Krstenansky, John L. ; Ahn, Jung Mo ; Azizeh, Bassem Y. ; Trivedi, Dev ; Hruby, Victor J. / Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon : The importance of charged residues and salt bridges in glucagon biological activity. In: Journal of Medicinal Chemistry. 1998 ; Vol. 41, No. 15. pp. 2693-2700.
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title = "Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon: The importance of charged residues and salt bridges in glucagon biological activity",
abstract = "We have designed and synthesized eight compounds 2-9 which incorporate various amino acid residues in positions 17, 18, and 21 of the glucagon molecule: 2, [Lys17]glucagon amide; 3, [Lys18]glucagon amide; 4, [Nle17,Lys18,Glu21]glucagon amide; 5, [Orn17,18 Glu21]glucagon amide; 6, [D-Arg17]glucagon; 7, [D-Arg18]glucagon; 8, [D- Phe17]glucagon; and 9, [D-Phe18]glucagon. Compared to glucagon (IC50 = 1.5 nM), analogues 2-9 were found to have binding affinity IC50 values (in nM) of 0.7, 4.1, 1.0, 2.0, 5.0, 25.0, 43.0, and 32.0, respectively. When these compounds were tested for their ability to stimulate adenylate cyclase (AC) activity, they were found to be full or partial agonists having maximum stimulation values of 100, 100, 100, 100, 87, 78, 94, and 100{\%}, respectively. On the basis of the X-ray crystal structure of [Lys17,18,Glu21]glucagon amide reported here, the ability to form a salt bridge between Lys18 and Glu21 is probably key to their increased binding and second messenger activities. Among the eight analogues synthesized here, only analogue 4 preserves the ability to form a salt bridge between Lys18 and Glu21. However, since these modifications are minor they do not seem to change the amphiphilic character of the C-terminus, allowing these analogues to reach 78-100{\%} stimulation in the adenylate cyclase assay. Biological data from analogues 6-9 supports the idea that position 18 of glucagon may influence binding only, while position 17 may influence both receptor recognition and transduction.",
author = "Sturm, {Noel S.} and Ying Lin and Burley, {Stephen K.} and Krstenansky, {John L.} and Ahn, {Jung Mo} and Azizeh, {Bassem Y.} and Dev Trivedi and Hruby, {Victor J}",
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T1 - Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon

T2 - The importance of charged residues and salt bridges in glucagon biological activity

AU - Sturm, Noel S.

AU - Lin, Ying

AU - Burley, Stephen K.

AU - Krstenansky, John L.

AU - Ahn, Jung Mo

AU - Azizeh, Bassem Y.

AU - Trivedi, Dev

AU - Hruby, Victor J

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N2 - We have designed and synthesized eight compounds 2-9 which incorporate various amino acid residues in positions 17, 18, and 21 of the glucagon molecule: 2, [Lys17]glucagon amide; 3, [Lys18]glucagon amide; 4, [Nle17,Lys18,Glu21]glucagon amide; 5, [Orn17,18 Glu21]glucagon amide; 6, [D-Arg17]glucagon; 7, [D-Arg18]glucagon; 8, [D- Phe17]glucagon; and 9, [D-Phe18]glucagon. Compared to glucagon (IC50 = 1.5 nM), analogues 2-9 were found to have binding affinity IC50 values (in nM) of 0.7, 4.1, 1.0, 2.0, 5.0, 25.0, 43.0, and 32.0, respectively. When these compounds were tested for their ability to stimulate adenylate cyclase (AC) activity, they were found to be full or partial agonists having maximum stimulation values of 100, 100, 100, 100, 87, 78, 94, and 100%, respectively. On the basis of the X-ray crystal structure of [Lys17,18,Glu21]glucagon amide reported here, the ability to form a salt bridge between Lys18 and Glu21 is probably key to their increased binding and second messenger activities. Among the eight analogues synthesized here, only analogue 4 preserves the ability to form a salt bridge between Lys18 and Glu21. However, since these modifications are minor they do not seem to change the amphiphilic character of the C-terminus, allowing these analogues to reach 78-100% stimulation in the adenylate cyclase assay. Biological data from analogues 6-9 supports the idea that position 18 of glucagon may influence binding only, while position 17 may influence both receptor recognition and transduction.

AB - We have designed and synthesized eight compounds 2-9 which incorporate various amino acid residues in positions 17, 18, and 21 of the glucagon molecule: 2, [Lys17]glucagon amide; 3, [Lys18]glucagon amide; 4, [Nle17,Lys18,Glu21]glucagon amide; 5, [Orn17,18 Glu21]glucagon amide; 6, [D-Arg17]glucagon; 7, [D-Arg18]glucagon; 8, [D- Phe17]glucagon; and 9, [D-Phe18]glucagon. Compared to glucagon (IC50 = 1.5 nM), analogues 2-9 were found to have binding affinity IC50 values (in nM) of 0.7, 4.1, 1.0, 2.0, 5.0, 25.0, 43.0, and 32.0, respectively. When these compounds were tested for their ability to stimulate adenylate cyclase (AC) activity, they were found to be full or partial agonists having maximum stimulation values of 100, 100, 100, 100, 87, 78, 94, and 100%, respectively. On the basis of the X-ray crystal structure of [Lys17,18,Glu21]glucagon amide reported here, the ability to form a salt bridge between Lys18 and Glu21 is probably key to their increased binding and second messenger activities. Among the eight analogues synthesized here, only analogue 4 preserves the ability to form a salt bridge between Lys18 and Glu21. However, since these modifications are minor they do not seem to change the amphiphilic character of the C-terminus, allowing these analogues to reach 78-100% stimulation in the adenylate cyclase assay. Biological data from analogues 6-9 supports the idea that position 18 of glucagon may influence binding only, while position 17 may influence both receptor recognition and transduction.

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