title: Single-walled carbon nanotube release affects the microbial enzyme-catalyzed oxidation processes of organic pollutants and lignin model compounds in nature.
abstract: The question how microbial enzyme-catalyzed oxidation processes of organic pollutants and lignin model compounds (LMCs) are affected by the release of single-walled carbon nanotube (SWCNT) into the environment remains to be addressed at the molecular level. We have, therefore concentrated the effects of SWCNT on some important properties associated with enzyme activity and function during microbial oxidation of polycyclic aromatic hydrocarbons (benzo(a)pyrene, acenaphthene and anthracene), LMCs (2,6-dimethoxyphenol, guaiacol and veratryl alcohol) and β-hexachlorocyclohexane, including the behaviour of water molecules, hydrogen bonds (HBs) and hydrophobic interactions (HYs) between ligand and the enzyme, and conformational dynamics in N- and C-terminus. Our study revealed that SWCNT significantly affected the behaviour of water molecules within 5 Å of both these substrates and their respective enzymes during oxidation (p < 0.01), by increasing or decreasing the water number near them. SWCNT tended to significantly enhance or reduce the stability of atom pairs that formed the HBs and HYs (p < 0.01). N- and C-terminus conformations underwent transitions between positive and negative states or between positive state or between negative state in all analyzed complexes. Significant conformational transitions were found for all C-terminus, but only for a part of N-terminus after the inclusion of the SWCNT. These results showed that SWCNT release would significantly affect the microbial enzyme-catalyzed processes of organic pollutants and LMCs in nature.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.affiliation: School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore. Electronic address: xsqin@ntu.edu.sg.
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Qin
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
mesh_terms: D001564:Benzo(a)pyrene / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D008031:Lignin / Q000378:metabolism; D037742:Nanotubes, Carbon / Q000737:chemistry; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D004798:Enzymes; D037742:Nanotubes, Carbon; D011084:Polycyclic Aromatic Hydrocarbons; D014867:Water; D001564:Benzo(a)pyrene; D008031:Lignin
keywords: Biodegradation; Carbon nanotube; Enzyme-catalyzed oxidation; Lignin; Organic pollutant; PAH