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2evq
From Proteopedia
(New page: 200px<br /><applet load="2evq" size="350" color="white" frame="true" align="right" spinBox="true" caption="2evq" /> '''Solution structure of HP7, a 12-residue beta...) |
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==Overview== | ==Overview== | ||
| - | Minimized beta hairpins have provided additional data on the geometric | + | Minimized beta hairpins have provided additional data on the geometric preferences of Trp interactions in TW-loop-WT motifs. This motif imparts significant fold stability to peptides as short as 8 residues. High-resolution NMR structures of a 16- (KKWTWNPATGKWTWQE, DeltaG(U)(298) >or= +7 kJ/mol) and 12-residue (KTWNPATGKWTE, DeltaG(U)(298) = +5.05 kJ/mol) hairpin reveal a common turn geometry and edge-to-face (EtF) packing motif and a cation-pi interaction between Lys(1) and the Trp residue nearest the C-terminus. The magnitude of a CD exciton couplet (due to the two Trp residues) and the chemical shifts of a Trp Hepsilon3 site (shifted upfield by 2.4 ppm due to the EtF stacking geometry) provided near-identical measures of folding. CD melts of representative peptides with the -TW-loop-WT- motif provided the thermodynamic parameters for folding, which reflect enthalpically driven folding at laboratory temperatures with a small DeltaC(p) for unfolding (+420 J K(-)(1)/mol). In the case of Asx-Pro-Xaa-Thr-Gly-Xaa loops, mutations established that the two most important residues in this class of direction-reversing loops are Asx and Gly: mutation to alanine is destabilizing by about 6 and 2 kJ/mol, respectively. All indicators of structuring are retained in a minimized 8-residue construct (Ac-WNPATGKW-NH(2)) with the fold stability reduced to DeltaG(U)(278) = -0.7 kJ/mol. NMR and CD comparisons indicate that -TWXNGKWT- (X = S, I) sequences also form the same hairpin-stabilizing W/W interaction. |
==About this Structure== | ==About this Structure== | ||
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Minimization and optimization of designed beta-hairpin folds., Andersen NH, Olsen KA, Fesinmeyer RM, Tan X, Hudson FM, Eidenschink LA, Farazi SR, J Am Chem Soc. 2006 May 10;128(18):6101-10. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16669679 16669679] | Minimization and optimization of designed beta-hairpin folds., Andersen NH, Olsen KA, Fesinmeyer RM, Tan X, Hudson FM, Eidenschink LA, Farazi SR, J Am Chem Soc. 2006 May 10;128(18):6101-10. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16669679 16669679] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Andersen, N | + | [[Category: Andersen, N H.]] |
| - | [[Category: Fesinmeyer, R | + | [[Category: Fesinmeyer, R M.]] |
| - | [[Category: Olsen, K | + | [[Category: Olsen, K A.]] |
[[Category: beta hairpin]] | [[Category: beta hairpin]] | ||
[[Category: peptide]] | [[Category: peptide]] | ||
[[Category: trp/trp packing]] | [[Category: trp/trp packing]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:15:08 2008'' |
Revision as of 15:15, 21 February 2008
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Solution structure of HP7, a 12-residue beta hairpin
Overview
Minimized beta hairpins have provided additional data on the geometric preferences of Trp interactions in TW-loop-WT motifs. This motif imparts significant fold stability to peptides as short as 8 residues. High-resolution NMR structures of a 16- (KKWTWNPATGKWTWQE, DeltaG(U)(298) >or= +7 kJ/mol) and 12-residue (KTWNPATGKWTE, DeltaG(U)(298) = +5.05 kJ/mol) hairpin reveal a common turn geometry and edge-to-face (EtF) packing motif and a cation-pi interaction between Lys(1) and the Trp residue nearest the C-terminus. The magnitude of a CD exciton couplet (due to the two Trp residues) and the chemical shifts of a Trp Hepsilon3 site (shifted upfield by 2.4 ppm due to the EtF stacking geometry) provided near-identical measures of folding. CD melts of representative peptides with the -TW-loop-WT- motif provided the thermodynamic parameters for folding, which reflect enthalpically driven folding at laboratory temperatures with a small DeltaC(p) for unfolding (+420 J K(-)(1)/mol). In the case of Asx-Pro-Xaa-Thr-Gly-Xaa loops, mutations established that the two most important residues in this class of direction-reversing loops are Asx and Gly: mutation to alanine is destabilizing by about 6 and 2 kJ/mol, respectively. All indicators of structuring are retained in a minimized 8-residue construct (Ac-WNPATGKW-NH(2)) with the fold stability reduced to DeltaG(U)(278) = -0.7 kJ/mol. NMR and CD comparisons indicate that -TWXNGKWT- (X = S, I) sequences also form the same hairpin-stabilizing W/W interaction.
About this Structure
2EVQ is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Minimization and optimization of designed beta-hairpin folds., Andersen NH, Olsen KA, Fesinmeyer RM, Tan X, Hudson FM, Eidenschink LA, Farazi SR, J Am Chem Soc. 2006 May 10;128(18):6101-10. PMID:16669679
Page seeded by OCA on Thu Feb 21 17:15:08 2008
