Surface-enhanced resonance Raman spectroscopy and spectroscopy study of redox-induced conformational equilibrium of cytochrome c adsorbed on DNA-modified metal electrode.
The redox-induced conformational equilibrium of cytochrome c (cyt c) adsorbed on DNA-modified metal electrode and the interaction mechanism of DNA with cyt c have been studied by electrochemical, spectroscopic and spectroelectrochemical techniques. The results indicate that the external electric field induces potential-dependent coordination equilibrium of the adsorbed cyt c between its oxidized state (with native six-coordinate low-spin and non-native five-coordinate high-spin heme configuration) and its reduced state (with native six-coordinate low-spin heme configuration) on DNA-modified metal electrode. The strong interactions between DNA and cyt c induce the self-aggregation of cyt c adsorbed on DNA. The orientational distribution of cyt c adsorbed on DNA-modified metal electrode is potential-dependent, which results in the deviation from an ideal Nernstian behavior of the adsorbed cyt c at high electrode potentials. The electric-field-induced increase in the activation barrier of proton-transfer steps attributed to the rearrangement of the hydrogen bond network and the self-aggregation of cyt c upon adsorption on DNA-modified electrode strongly decrease the interfacial electron transfer rate. In addition, the strongly Coulombic interactions between DNA and cyt c only disturb the microenvironment of the heme, and do not affect the states of heme ligation and spin. The secondary structure of the adsorbed cyt c is retained, while the conformation of DNA is changed from the B form DNA to A form DNA.
Jiang
Xiue
X
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Changchun, Jilin 130022, China.
Wang
Yuling
Y
Qu
Xiaohu
X
Dong
Shaojun
S
D000327:Adsorption; D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D045304:Cytochromes c / Q000032:analysis* / Q000737:chemistry* / Q000493:pharmacokinetics; D004247:DNA; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold; D006736:Horses; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman
D006046:Gold; D045304:Cytochromes c; D004247:DNA