Effect of mono-CDNP substitution of lysine residues on the redox reaction of cytochrome c electrostatically adsorbed on a mercaptoheptanoic acid modified Au(111) surface

Shin Ichiro Imabayashi, Takahiro Mita, Takashi Kakiuchi

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The effect of charge-inverting modification of single surface lysine residue on the electron transfer (ET) reaction of horse heart cytochrome c (cyt c) is examined for 12 different types of mono-4-chloro-2,5-dinitrobenzoic acid substituted cyt c (mCDNPc) adsorbed on a Au(111) electrode modified with a self-assembled monolayer (SAM) of 7-mercapto-heptanoic acid (MHA). A negative shift in the redox potential by 10-35 mV as compared to that of native cyt c and a monolayer coverage in the range of 13-17 pmol cm-2 are observed for electroactive mCDNPc's. The magnitude of the decrease in the ET rate constant (ket) of mCDNPc's compared with that of native cyt c depends on the position of the CDNP substitution. For mCDNPc's in which the modified lysine residue is outside of the interaction domain of cyt c with the SAM, the ratio of the ket of mCDNPc to that of native cyt c is correlated to the change in the dipole moment vector of cyt c due to the CDNP modification. This correlation suggests that the dipole moment of cyt c determines its orientation of adsorption on the SAM of MHA and significantly affects the rate of the ET. The CDNP modification of lysine residues at the interaction domain significantly decreases the rate, demonstrating the importance of the local charge environment in determining the rate of ET.

Original languageEnglish
Pages (from-to)2474-2479
Number of pages6
JournalLangmuir
Volume21
Issue number6
DOIs
Publication statusPublished - 2005 Mar 15

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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