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Mechanisms for the Direct Electron Transfer of Cytochrome c Induced by Multi-Walled Carbon Nanotubes
Department of Environmental Engineering, Peking University, Beijing 100871, China
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China
School of Food and Bioengineering, Shandong Institute of Light Industry, Jinan 250353, China
* Author to whom correspondence should be addressed.
Received: 18 June 2012; in revised form: 17 July 2012 / Accepted: 17 July 2012 / Published: 2 August 2012
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.
Keywords: direct electron transfer (DET); cytochrome c (Cyt c); multi-walled carbon nanotube (MWCNT); secondary structure
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Zhao, H.-Z.; Du, Q.; Li, Z.-S.; Yang, Q.-Z. Mechanisms for the Direct Electron Transfer of Cytochrome c Induced by Multi-Walled Carbon Nanotubes. Sensors 2012, 12, 10450-10462.
Zhao H-Z, Du Q, Li Z-S, Yang Q-Z. Mechanisms for the Direct Electron Transfer of Cytochrome c Induced by Multi-Walled Carbon Nanotubes. Sensors. 2012; 12(8):10450-10462.
Zhao, Hua-Zhang; Du, Qian; Li, Zhen-Shan; Yang, Qin-Zheng. 2012. "Mechanisms for the Direct Electron Transfer of Cytochrome c Induced by Multi-Walled Carbon Nanotubes." Sensors 12, no. 8: 10450-10462.