2evq
From Proteopedia
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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 Tue Jan 29 19:22:24 2008
