Minimization and Optimization of Designed -Hairpin Folds
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- 作者：Niels H. Andersen ; Katherine A. Olsen ; R. Matthew Fesinmeyer ; Xu Tan ; F. Michael Hudson ; Lisa A. Eidenschink ; and Shabnam R. Farazi
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：May 10, 2006
- 年：2006
- 卷：128
- 期：18
- 页码：6101 - 6110
- 全文大小：325K
- 年卷期：v.128,no.18(May 10, 2006)
- ISSN：1520-5126
文摘
Minimized 
hairpins have provided additional data on the geometric preferences of Trpinteractions in TW-loop-WT motifs. This motif imparts significant fold stability to peptides as short as 8residues. High-resolution NMR structures of a 16- (KKWTWNPATGKWTWQE, 
GU298 
+7 kJ/mol) and12-residue (KTWNPATGKWTE, GU298 = +5.05 kJ/mol) hairpin reveal a common turn geometry and edge-to-face (EtF) packing motif and a cation-
pi.gif" BORDER=0 > interaction between Lys1 and the Trp residue nearest theC-terminus. The magnitude of a CD exciton couplet (due to the two Trp residues) and the chemical shiftsof a Trp H
psilon.gif" BORDER=0 >3 site (shifted upfield by 2.4 ppm due to the EtF stacking geometry) provided near-identicalmeasures of folding. CD melts of representative peptides with the -TW-loop-WT- motif provided thethermodynamic parameters for folding, which reflect enthalpically driven folding at laboratory temperatureswith a small Cp for unfolding (+420 J K-1/mol). In the case of Asx-Pro-Xaa-Thr-Gly-Xaa loops, mutationsestablished 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 areretained in a minimized 8-residue construct (Ac-WNPATGKW-NH2) with the fold stability reduced to GU278= -0.7 kJ/mol. NMR and CD comparisons indicate that -TWXNGKWT- (X = S, I) sequences also form thesame hairpin-stabilizing W/W interaction.
hairpins have provided additional data on the geometric preferences of Trpinteractions in TW-loop-WT motifs. This motif imparts significant fold stability to peptides as short as 8residues. High-resolution NMR structures of a 16- (KKWTWNPATGKWTWQE, GU298 +7 kJ/mol) and12-residue (KTWNPATGKWTE, GU298 = +5.05 kJ/mol) hairpin reveal a common turn geometry and edge-to-face (EtF) packing motif and a cation-pi.gif" BORDER=0 > interaction between Lys1 and the Trp residue nearest theC-terminus. The magnitude of a CD exciton couplet (due to the two Trp residues) and the chemical shiftsof a Trp Hpsilon.gif" BORDER=0 >3 site (shifted upfield by 2.4 ppm due to the EtF stacking geometry) provided near-identicalmeasures of folding. CD melts of representative peptides with the -TW-loop-WT- motif provided thethermodynamic parameters for folding, which reflect enthalpically driven folding at laboratory temperatureswith a small Cp for unfolding (+420 J K-1/mol). In the case of Asx-Pro-Xaa-Thr-Gly-Xaa loops, mutationsestablished 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 areretained in a minimized 8-residue construct (Ac-WNPATGKW-NH2) with the fold stability reduced to GU278= -0.7 kJ/mol. NMR and CD comparisons indicate that -TWXNGKWT- (X = S, I) sequences also form thesame hairpin-stabilizing W/W interaction.