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Mechanisms for the direct electron transfer of cytochrome c induced by multi-walled carbon nanotubes.

Zhao HZ, Du Q, Li ZS, Yang QZ - Sensors (Basel) (2012)

Bottom Line: There are several possible mechanisms that explain the DET of Cyt c.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering, Peking University, Beijing 100871, China. zhaohuazhang@pku.edu.cn

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.

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UV-vis absorption spectra of MWCNTs, Cyt c, and Cyt c/MWCNTs.
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f5-sensors-12-10450: UV-vis absorption spectra of MWCNTs, Cyt c, and Cyt c/MWCNTs.

Mentions: The spatial orientation of the heme porphyrin ring, which may be a factor that affects electron transfer, was investigated by UV-vis absorption spectroscopy, as shown in Figure 5. There is no absorption observed in Figure 5 for the black MWCNT particles. The spectrum of Cyt c exhibits two obvious UV absorption peaks at 409 and 528 nm, corresponding to the Soret band and Q-band of Cyt c, respectively. The spectrum of Cyt c immobilized on MWCNTs also shows a Soret band with a decrease in intensity and a hypsochromic shift of only 1 nm to 408 nm.


Mechanisms for the direct electron transfer of cytochrome c induced by multi-walled carbon nanotubes.

Zhao HZ, Du Q, Li ZS, Yang QZ - Sensors (Basel) (2012)

UV-vis absorption spectra of MWCNTs, Cyt c, and Cyt c/MWCNTs.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472837&req=5

f5-sensors-12-10450: UV-vis absorption spectra of MWCNTs, Cyt c, and Cyt c/MWCNTs.
Mentions: The spatial orientation of the heme porphyrin ring, which may be a factor that affects electron transfer, was investigated by UV-vis absorption spectroscopy, as shown in Figure 5. There is no absorption observed in Figure 5 for the black MWCNT particles. The spectrum of Cyt c exhibits two obvious UV absorption peaks at 409 and 528 nm, corresponding to the Soret band and Q-band of Cyt c, respectively. The spectrum of Cyt c immobilized on MWCNTs also shows a Soret band with a decrease in intensity and a hypsochromic shift of only 1 nm to 408 nm.

Bottom Line: There are several possible mechanisms that explain the DET of Cyt c.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering, Peking University, Beijing 100871, China. zhaohuazhang@pku.edu.cn

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.

Show MeSH