Molecular Mechanism of Interaction and Electron Transfer Between Dihydric Phenols and L-Cysteine

The mechanism and electron transfer for pollutant dihydric phenol and biomolecule L-Cysteine (L-Cys) interaction in aqueous solution were studied by means of electrochemistry and UV-VIS spectrophotometry. Two forms of L-Cys, fixed on Au-electrode and free dissolved in the solution, were examined. The results showed that L-Cys of an ordered monolayer fixed on an Au electrode facilitated electron transfer and electrocatalytic redox of three isomers of dihydric phenol. However, free L-Cys does not show such facility. Furthermore, neither cleavage of the original chemical bond nor formation of a new chemical bond was observed in the molecules investigated, suggesting that L-Cys molecules may associate tightly with dihydric phenol molecules to form L-Cys · C₆H₆O₂or (L-Cys) ₂ · C₆H₆O₂ complex molecule via hydrogen-bonding. Different coordination numbers influence the electrochemical activity and behavior of associated complexes; thus, the function of biomolecules could be affected.

Keywords:

• L-Cysteine
• Dihydric phenol
• Cyclic Voltammetry
• Interaction
• Molecular mechanism
• Electron transfer.

ACKNOWLEDGMENTS

The research is supported by the National Natural Science Foundation of China (Project No. 50478106) and Nanometer Science Foundation of Shanghai, China (Project No. 0452 nm075).