Minimization and optimization of designed β-hairpin folds
Minimization and optimization of designed β-hairpin folds
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DOI：
10.1021/ja054971w
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发表时间：
2006-05-10
影响因子：
15
通讯作者：
Farazi, Shabnam R.
中科院分区：
文献类型：
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作者：
Andersen, Niels H.;Olsen, Katherine A.;Farazi, Shabnam R.
最小化的发夹提供了关于 TW-loop-WT 基序中色氨酸相互作用的几何偏好的额外数据。该基序赋予短至 8 个残基的肽显着的折叠稳定性。 16-(KKWTWNPATGKWTWQE, Delta G(U)(298) >= + 7 kJ/mol) 和 12-残基 (KTWNPATGKWTE, Delta G(U)(298) = + 5.05 kJ/mol) 发夹的高分辨率 NMR 结构揭示了常见的转弯几何结构和边对面 (EtF) 堆积图案和 Lys(1) 和最靠近 C 末端的 Trp 残基之间的阳离子-π 相互作用。 CD 激子对的大小（由于两个色氨酸残基）和色氨酸 H 的化学位移是 3 个位点的元素（由于 EtF 堆叠几何结构，向上场移动 2.4 ppm），提供了几乎相同的折叠测量。具有 -TW-loop-WT-基序的代表性肽的 CD 熔解提供了折叠的热力学参数，这反映了实验室温度下的焓驱动折叠，具有用于去折叠的小 Delta C-p (+ 420 J K-1/mol)。对于 Asx-Pro-Xaa-Thr-Gly-Xaa 环，突变确定了此类方向反转环中两个最重要的残基是 Asx 和 Gly：丙氨酸突变分别导致约 6 kJ/mol 和 2 kJ/mol 的不稳定。所有结构指标均保留在最小化的 8 残基构建体 (Ac-WNPATGKW-NH2) 中，倍数稳定性降低至 Delta G(U)(278) = - 0.7 kJ/ mol。 NMR 和 CD 比较表明 -TWXNGKWT-(X = S, I) 序列也形成相同的发夹稳定 W/W 相互作用。
Minimized, 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, Delta G(U)(298) >= + 7 kJ/ mol) and 12-residue (KTWNPATGKWTE, Delta G(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 H is an element of 3 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 Delta C-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-NH2) with the fold stability reduced to Delta G(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.