Res. Chem. Intermed.
, Vol. 27, No. 7,8, pp. 717–723 (2001)
Peroxidase-like activity of cytochrome c in the presence
of anionic surfactants
LIDIA G ¸EBICKA
Institute of Applied Radiation Chemistry, Technical University of ód´z, Poland
Abstract—Peroxidase-like activity of cytochrome c is signi cantly higher in the presence of anionic
surfactants, sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium n-dodecyl sulphate (SDS).
The enhancement is due to the higher reaction rate of the cytochrome c with H
, which is the
rate determining step in the peroxidase cycle of cytochrome c. An intermediate formed in the cycle
rapidly oxidizes the substrates or reacts with further molecule(s) of H
, causing heme degradation.
Thus, the speci c microenvironment provided by anionic surfactants facilitates also degradation of
heme iron by H
Cytochrome c which participates in the electron transfer processes in biomembranes
is composed of a single polypeptide chain covalently bound to the heme group.
In the native state the heme iron is ligated by His18 and Met80. The Met80-iron
bond readily disrupts either upon the addition of heme iron ligands or denaturants.
Changes in ionic strength, pH or temperature also cause deligation of methionine
Cytochrome c in its native form has been reported to display very weak peroxi-
dase-like activity [6 – 8]. It has been shown that in the presence of H
c can initiate lipid peroxidation and protein damage . The general mechanism of
peroxidase catalytic cycle is given below:
Peroxidase C H
! Compound I, (1)
Compound I C AH
! Compound II C AH
Compound II C AH
! Peroxidase C AH
where Compound I is ferryl (Fe(IV) D O) radical, Compound II is ferryl derivative
of enzyme and AH
is the molecule undergoing oxidation.