Primary role of peroxidase enzyme is to decompose endogenous hydrogen
peroxide, when oxygen radical is being replaced by a less potent radical,
which is its cosubstrates oxidized form. During this study, catalytic
activity of horseradish peroxidase has been observed in the presence of
antioxidants from vitamin group, such as C, E and A, i.e. their water-soluble
forms. It was found that vitamin E showed no effect on the enzyme activity
and fate of cosubstrate radicals from the group of benzidine derivatives.
Vitamin C proceeds enzymatic reaction showing its antioxidative character,
and absorbs electrons from radicals, bringing cosubstrate back to its relaxed
state. On the other hand, vitamin A plays a role of uncompetitive peroxidase
inhibitor, which is visible through decreasing initial rate of catalytic
reaction, and is reflected as virtual decrease of enzyme concentration.
Furthermore, it prolongs life of endogenous hydrogen peroxide, which could
potentially lead to oxidative stress of cells. This inhibitory effect can be
used in analytical purpose, for determination of retinol acetate content in a
sample.
Inhibitory effect of retinol acetate on horseradish peroxidase
