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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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Far-UV CD spectra of Cyt c and Cyt c/MWCNTs.
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f4-sensors-12-10450: Far-UV CD spectra of Cyt c and Cyt c/MWCNTs.

Mentions: The far-UV CD spectra of native Cyt c and Cyt c immobilized on MWCNTs exhibit two negative peaks at 208 and 221 nm resulting from the chirality of alpha-helical structures (Figure 4). These results are similar to those of previous reports [38,39]. Absorption in the region below 240 nm is due primarily to the peptide bond. Therefore, it can be concluded from the CD spectra that the structure and activity of Cyt c after being treated with MWCNTs are essentially the same as in the native protein. The secondary structure content of the native and the treated Cyt c were calculated and the results are compared with the corresponding results of FTIR spectra as follows.


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)

Far-UV CD spectra of Cyt c and Cyt c/MWCNTs.
© Copyright Policy
Related In: Results  -  Collection

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

f4-sensors-12-10450: Far-UV CD spectra of Cyt c and Cyt c/MWCNTs.
Mentions: The far-UV CD spectra of native Cyt c and Cyt c immobilized on MWCNTs exhibit two negative peaks at 208 and 221 nm resulting from the chirality of alpha-helical structures (Figure 4). These results are similar to those of previous reports [38,39]. Absorption in the region below 240 nm is due primarily to the peptide bond. Therefore, it can be concluded from the CD spectra that the structure and activity of Cyt c after being treated with MWCNTs are essentially the same as in the native protein. The secondary structure content of the native and the treated Cyt c were calculated and the results are compared with the corresponding results of FTIR spectra as follows.

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