NMR Solution Structure of the Glucagon Antagonist [desHis1, desPhe6, Glu9]Glucagon Amide in the Presence of Perdeuterated Dodecylphosphocholine Micelles
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- 作者：Jinfa Ying ; Jung-Mo Ahn ; Neil E. Jacobsen ; Michael F. Brown ; and Victor J. Hruby
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：March 18, 2003
- 年：2003
- 卷：42
- 期：10
- 页码：2825 - 2835
- 全文大小：444K
- 年卷期：v.42,no.10(March 18, 2003)
- ISSN：1520-4995
文摘
Glucagon, a 29-residue peptide hormone, plays an important role in glucose homeostasis andin diabetes mellitus. Several glucagon antagonists and agonists have been developed, but limited structuralinformation is available to clarify the basis of their biological activity. The solution structure of the potentglucagon antagonist, [desHis1, desPhe6, Glu9]glucagon amide, was determined by homonuclear 2D NMRspectroscopy at pH 6.0 and 37 
C in perdeuterated dodecylphosphocholine micelles. The overall backboneroot-mean-square deviation (rmsd) for the structured portion (residues 7-29, glucagon numbering) of themicelle-bound 27-residue peptide is 1.36 Å for the 15 lowest-energy structures, after restrained moleculardynamics simulation. The structure consists of four regions (segment backbone rmsd in Å): an unstructuredN-terminal segment between residues 2 and 5 (1.68), an irregular helix between residues 7 and 14 (0.79),a hinge region between residues 15 and 18 (0.54), and a well-defined 
-helix between residues 19 and 29(0.33). The two helices form an L-shaped structure with an angle of about 90 between the helix axes.There is an extended hydrophobic cluster, which runs along the inner surface of the L-structure andincorporates the side chains of the hydrophobic residues of each of the amphipathic helices. The outersurface contains the hydrophilic side chains, with two salt bridges (D15-R18 and R17-D21) implied fromclose approach of the charged groups. This result is the first clear indication of an overall tertiary fold fora glucagon analogue in the micelle-bound state. The relationship of the two helical structural elementsmay have important implications for the biological activity of the glucagon antagonist.
C in perdeuterated dodecylphosphocholine micelles. The overall backboneroot-mean-square deviation (rmsd) for the structured portion (residues 7-29, glucagon numbering) of themicelle-bound 27-residue peptide is 1.36 Å for the 15 lowest-energy structures, after restrained moleculardynamics simulation. The structure consists of four regions (segment backbone rmsd in Å): an unstructuredN-terminal segment between residues 2 and 5 (1.68), an irregular helix between residues 7 and 14 (0.79),a hinge region between residues 15 and 18 (0.54), and a well-defined -helix between residues 19 and 29(0.33). The two helices form an L-shaped structure with an angle of about 90 between the helix axes.There is an extended hydrophobic cluster, which runs along the inner surface of the L-structure andincorporates the side chains of the hydrophobic residues of each of the amphipathic helices. The outersurface contains the hydrophilic side chains, with two salt bridges (D15-R18 and R17-D21) implied fromclose approach of the charged groups. This result is the first clear indication of an overall tertiary fold fora glucagon analogue in the micelle-bound state. The relationship of the two helical structural elementsmay have important implications for the biological activity of the glucagon antagonist.