title: Mechanisms for the direct electron transfer of cytochrome c induced by multi-walled carbon nanotubes.
abstract: Multi-walled carbon nanotube (MWCNT)-modified electrodes can promote the direct electron transfer (DET) of cytochrome c (Cyt c). There are several possible mechanisms that explain the DET of Cyt c. In this study, several experimental methods, including Fourier transform infrared spectroscopy, circular dichroism, ultraviolet-visible absorption spectroscopy, and electron paramagnetic resonance spectroscopy were utilized to investigate the conformational changes of Cyt c induced by MWCNTs. The DET mechanism was demonstrated at various nano-levels: secondary structure, spatial orientation, and spin state. In the presence of MWCNTs, the secondary structure of Cyt c changes, which exposes the active site, then, the orientation of the heme is optimized, revolving the exposed active center to the optimum spatial orientation for DET; and finally, a transition of spin states is induced, providing relatively high energy and a more open microenvironment for electron transfer. These changes at different nano-levels are closely connected and form a complex process that promotes the electron transfer of Cyt c.
authors.affiliation: Department of Environmental Engineering, Peking University, Beijing 100871, China. zhaohuazhang@pku.edu.cn
authors.forename: Hua-Zhang
authors.initials: HZ
authors.lastname: Zhao
authors.forename: Qian
authors.initials: Q
authors.lastname: Du
authors.forename: Zhen-Shan
authors.initials: ZS
authors.lastname: Li
authors.forename: Qin-Zheng
authors.initials: QZ
authors.lastname: Yang
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004583:Electrons; D006736:Horses; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D037742:Nanotubes, Carbon; D045304:Cytochromes c
keywords: cytochrome c (Cyt c); direct electron transfer (DET); multi-walled carbon nanotube (MWCNT); secondary structure