Electrochemistry of oriented cytochrome c monolayer on modified gold electrode and Its in situ denaturation in organic/aqueous medium

چکیده مقاله

Cytochrome c (Cyt c) was absorbed on gold electrode modified with a
mixture (1:3) of 11-mercapto-1-undecanol and 11-mercaptoundecanoic acid (C11)
solutions. The Cyt c/C11/Au electrode thus prepared showed a well-defined quasi
reversible voltammetric peak with electron transfer rate constant of 234 s-1. The surface
coverage of Cyt c oriented on the surface of C11-modified electrode was determined to
be 4.73×10-11 mol cm-2. The Cyt c/C11/Au electrode linearly responded to H2O2 in the
concentration range from 90 to 500 μM with a correlation coefficient of 0.9973. Using
the reciprocal plot of the steady state current versus hydrogen peroxide concentration,
apparent Michaelis constant for the Cyt c was estimated to be 759 μM. In addition,
voltammetric analysis was used to study the in situ denaturation of the immobilized Cyt
c by gradual addition of either urea up to 8 M or dimethyl formamide (DMF) up to 55%.
It was revealed that the mechanism of Cyt c denaturation depends on media (organic or
aqueous) were used. So that in the presence of DMF it follows a two-phase process,
whereas in urea containing buffer solution, it pursues a single-phase course.