title: Sodium hexadecyl sulfate as an interfacial substance adjusting the adsorption of a protein on carbon nanotubes.
abstract: Carbon nanotubes (CNTs) were functionalized with sodium hexadecyl sulfate (SHS). The lysozyme adsorbed on the SHS-CNTs exhibited a higher activity than that immobilized on the nonfunctionalized CNTs. To explain the experimental results and explore the mechanism of lysozyme adsorption, large-scale molecular dynamics simulations have been performed for a four-component system, including lysozyme, SHS, CNTs in explicit water. It has been found that the assembled SHS molecules form a soft layer on the surface of CNTs. The interactions between lysozyme and SHS induce the rearrangement of SHS molecules, forming a saddle-like structure on the CNT surface. The saddle-like structure fits the shape of the lysozyme, and the active-site cleft of the lysozyme is exposed to the water phase. Whereas, for the lysozyme adsorbed on the nonfunctionalized CNT, due to the hydrophobic interactions, the active-site cleft of the enzyme tends to face the wall of the CNT. The results of this work demonstrate that the SHS molecules as the interfacial substance have a function of adjusting the lysozyme with an appropriate orientation, which is favorable for the lysozyme having a higher activity.
authors.affiliation: Beijing Key Lab of Bioprocess, Department of Biochemical Engineering and ‡Department of Chemical Engineering, Beijing University of Chemical Technology , Beijing, 100029, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Kun
authors.initials: K
authors.lastname: Du
authors.forename: Li
authors.initials: L
authors.lastname: Fu
authors.forename: Jiang
authors.initials: J
authors.lastname: Gao
authors.forename: Haiyang
authors.initials: H
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Peijun
authors.initials: P
authors.lastname: Ji
mesh_terms: D000327:Adsorption; D003198:Computer Simulation; D019277:Entropy; D009113:Muramidase / Q000302:isolation & purification*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D013431:Sulfates; D013501:Surface-Active Agents; D014867:Water; C012036:sodium sulfate; D009113:Muramidase
keywords: carbon nanotubes; lysozyme; molecular dynamics simulation; sodium hexadecyl sulfate