STUDENT ABSTRACTS - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 271

Oxidative stress caused by tropospheric ozone on some biomolecules
MARIA GIUBELAN , AURELIA MEGHEA, MARIA GIURGINCA, ALIN MIHALY
University “Politehnica” of Bucharest, National Consultancy Center for Environmental
Protection, Bucharest, Romania

Living cells acting as “cell factories” are directly involved into fundamental
processes of metabolism. Sometimes in such biochemical reactions the active species of
oxygen are also involved. As a result of oxidative reactions accelerated by stress and
pollution, a number of short life radicals and oxygenated compounds are formed which
affect the metabolism of the main constituents of cells, protein and aminoacids, giving
rise to premature aging and diseases by damaging the functioning of vital organs. The
aim of this paper is to evidence the involvement of ozone during oxidative process of
some aromatic aminoacids, tryptophane (Trp), tyrosine (Tyr) and hystidine (His).
The UV-VIS spectroscopy and
chemiluminescence experiments were
used in this study. The main kinetic
characteristics were determined to
interpret the mechanism of the processes.
The ozone was generated in ozonation
plant. The tryptophane (see Figure)
changes through by ozonation for
example; the 271 and 287 nm bands
change hypsochromously by 20 nm and
presents a new band at 314 nm.
Kinetic characteristics of ozonation
process is presented in the following table for the debit (5 L/h) of ozone. The resulting
products by ozonation were tested by chemiluminescence technique. The conclusion is a
decrease in the antioxidant effect of the tryptophane. This characteristic is presented
also by other aminoacids as a results of the prooxidant effect of the newly formed
ketonic compounds.

4

1 - initial 2 - 10 s

Abs 1

3 - 30 s 4 - 60 s

5 - 120 s

3

2

3
4
5

2

1

0

200 300 400

Wavelength [nm]

AA Reaction order Rate constant Comments

His 1 0.0893 -

Trp 2 0.0027 -

1.2
1.3

0.0059
0.0054

first 30 s
after 30 s

Tyr

The oxidative stress of ozone on some biomolecules results in structural changes
in the initial molecules. The kinetic of ozone reaction with the tested biomolecules has a
reaction order 1 or 2, showing the complexity of the process. The effect of ozone on the
tested biomolecules is change of the antioxidant character into prooxidant.