THE CHANGES IN ACTIVITY OF ATPase AND ANTIOXIDANT ENZYMES, AND PROLINE
BIOSYNTHESIS IN YEASTS Candida guilliermondii NP-4 UNDER INFLUENCE OF
X-IRRADIATION
Abstract
This study aimed to investigate the effect of X-radiation on the ATPase
activity and the activity of antioxidant enzymes, including enzymes of
proline biosynthesis, in C. guilliermondii NP-4 yeast cells after
X-irradiation and the post-irradiation repair of cells. It has been
shown that the X-irradiation of yeasts C. guilliermondii NP-4 at
a dose of 300 Gy causes the increase of activity of the enzymes catalase
and SOD and the ratio of catalase/SOD. The repair of radiation-induced
damages requires a lot of energy, so the demand for ATP increases in
irradiated and repaired yeasts. The total and FoF
1-ATPase activity in yeast homogenates and mitochondria
increases after X-irradiation and post-irradiation repair. Amino acid
proline is an antioxidative defense molecule and plays a significant
role in the adaptation of cells to stress. So higher proline levels in
yeasts can protect them from oxidative damage. There are still no
systematic studies of the antioxidant properties of proline. In this
study, it has been shown that the activity of enzymes of proline
biosynthesis (ornithine transaminase and proline-5-carboxylate
reductase) in yeasts C.guilliermondii NP-4 increases after
X-irradiation and remains higher after post-irradiation repair.
Connected with it, the proline amount in X-irradiated and repaired
yeasts also is higher than in non-irradiated cells. We suppose that
proline has a radioprotective effect on X-irradiated yeasts C.
guilliermondii NP-4.