Tang Y, Ghirlanda G, Vaidehi N, Kua J, Mainz D T, Goddard III W A, DeGrado W F, Tirrell D A
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Biochemistry. 2001 Mar 6;40(9):2790-6. doi: 10.1021/bi0022588.
Substitution of leucine residues by 5,5,5-trifluoroleucine at the d-positions of the leucine zipper peptide GCN4-p1d increases the thermal stability of the coiled-coil structure. The midpoint thermal unfolding temperature of the fluorinated peptide is elevated by 13 degrees C at 30 microM peptide concentration. The modified peptide is more resistant to chaotropic denaturants, and the free energy of folding of the fluorinated peptide is 0.5-1.2 kcal/mol larger than that of the hydrogenated form. A similarly fluorinated form of the DNA-binding peptide GCN4-bZip binds to target DNA sequences with affinity and specificity identical to those of the hydrogenated form, while demonstrating enhanced thermal stability. Molecular dynamics simulation on the fluorinated GCN4-p1d peptide using the Surface Generalized Born implicit solvation model revealed that the coiled-coil binding energy is 55% more favorable upon fluorination. These results suggest that fluorination of hydrophobic substructures in peptides and proteins may provide new means of increasing protein stability, enhancing protein assembly, and strengthening receptor-ligand interactions.
在亮氨酸拉链肽GCN4-p1d的d位用5,5,5-三氟亮氨酸取代亮氨酸残基可提高卷曲螺旋结构的热稳定性。在30 microM肽浓度下，氟化肽的热解链中点温度升高了13摄氏度。修饰后的肽对离液变性剂更具抗性，且氟化肽的折叠自由能比氢化形式的大0.5-1.2千卡/摩尔。DNA结合肽GCN4-bZip的类似氟化形式以与氢化形式相同的亲和力和特异性结合靶DNA序列，同时表现出增强的热稳定性。使用表面广义玻恩隐式溶剂化模型对氟化GCN4-p1d肽进行的分子动力学模拟表明，氟化后卷曲螺旋结合能更有利55%。这些结果表明，肽和蛋白质中疏水亚结构的氟化可能为提高蛋白质稳定性、增强蛋白质组装以及加强受体-配体相互作用提供新方法。
