Molecular Dynamics Study of a Nanotube-Binding Amphiphilic Helical Peptide at Different Water/Hydrophobic Interfaces
Molecular Dynamics Study of a Nanotube-Binding Amphiphilic Helical Peptide at Different Water/Hydrophobic Interfaces
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DOI：
10.1021/jp805313p
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发表时间：
2008-12-25
影响因子：
3.3
通讯作者：
Nielsen, Steven O.
中科院分区：
文献类型：
--
作者：
Chiu, Chi-cheng;Dieckmann, Gregg R.;Nielsen, Steven O.
单壁碳纳米管(SWNTs)的许多潜在应用要求它们彼此隔离。这可以通过共价或非共价SWNT官能化来实现。非共价法保留了单壁碳纳米管固有的电学、光学和力学性质，可以通过使用表面活性剂、聚合物或生物大分子如DNA或多肽将其分散在水溶液中来实现。所设计的两亲性螺旋肽NANO-1含有疏水的缬氨酸和芳香族苯丙氨酸残基用于与单壁碳纳米管的相互作用，以及谷氨酸和赖氨酸残基的水溶性，已经被证明可以分散和分散单壁碳纳米管，尽管多肽与单壁碳纳米管相互作用的细节还有待阐明。在这里，我们使用全原子分子动力学模拟来研究纳米1肽在三种不同的水/疏水界面：水/油、水/石墨和水/单壁碳纳米管。多肽的两亲性特征是其二级结构、多肽-水氢键和多肽-疏水表面范德华能量。我们发现，由于多肽螺旋穿透到疏水相中，纳米1分子在水/油界面的两亲性有所降低。在不部分展开的情况下，多肽α-螺旋不能使其疏水表面与刚性平面石墨表面匹配。相比之下，Nano-1可以以α-螺旋构象在单壁碳纳米管表面弯曲，同时最大化其与单壁碳纳米管的疏水接触以及与水的氢键。对不同疏水表面上的多肽构象的分子洞察为未来的多肽设计提供了指导。
Many potential applications of single-walled carbon nanotubes (SWNTs) require that they be isolated from one another. This may be accomplished through covalent or noncovalent SWNT functionalization. The noncovalent approach preserves the intrinsic electrical, optical, and mechanical properties of SWNTs and can be achieved by dispersing SWNTs in aqueous solution using surfactants, polymers, or biomacromolecules like DNA or polypeptides. The designed amphiphilic helical peptide nano-1, which contains hydrophobic valine and aromatic phenylalanine residues for interaction with SWNTs and glutamic acid and lysine residues for water solubility, has been shown to debundle and disperse SWNTs, although the details of the peptide-SWNT interactions await elucidation. Here we use fully atomistic molecular dynamics simulations to investigate the nano-1 peptide at three different water/hydrophobic interfaces: water/oil, water/graphite, and water/SWNT. The amphiphilic nature of the peptide is characterized by its secondary structure, peptide-water hydrogen bonding, and peptide-hydrophobic surface van der Waals energy. We show that nano-1 has reduced amphiphilic character at the water/oil interface because the peptide helix penetrates into the hydrophobic phase. The peptide alpha-helix cannot match its hydrophobic face to the rigid planar graphite surface without partially unfolding. In contrast, nano-1 can curve on the SWNT surface in an alpha-helical conformation to simultaneously maximize its hydrophobic contacts with the SWNT and its hydrogen bonds with water. The molecular insight into the peptide conformation at the various hydrophobic surfaces provides guidelines for future peptide design.