As a result of electron microscopic studies of morphogenesis in yeast Candida guilliermondii NP‐4, the formation of new structures of volutin acidocalcisomes has been established within the cell cytoplasm. Under influence of X‐irradiation, the changes in morphometric and electron‐dense properties of yeast cells were identified: in yeast cytoplasm, the electron‐dense volutin granules were increased up to 400 nm in size. After 24‐h post‐irradiation incubation of yeasts, the large volutin pellets are fragmented into smaller number particles in size up to 25–150 nm. The ATPase activity in yeast mitochondria was changed under X‐irradiation. In latent phase of growth, ATPase activity was decreased 1·35‐fold in comparison with non‐irradiated yeasts. In logarithmic phase of growth, ATPase activity was three times higher than in latent phase, and in stationary phase of growth it has a value similar to the latent phase. Probably, the cells receive the necessary energy from alternative energy sources, such as volutin. Electron microscopy of volutin granule changes might serve as convenient method for evaluation of damages and repair processes in cells under influence of different environmental stress‐factors.

In metabolism of living cells a key role play purine nucleotides which cells can be supplied either by de novo synthesis from lower molecular weight precursors, or by alternate ways of nucleotide synthesis or so-called "nucleotide salvage pathways", which allow reusing of intermediate products of nucleotide metabolism in nucleotide synthesis. This way is important in the post-stress repair period, saving energy and substrates in the repairing cells. Purine nucleotides are allosteric inhibitors of enzymes of nucleotide salvage pathways, therefore the increase in their catabolism leads to a decrease of their amount in the cells, which contributes to the intensive work of the nucleotide salvage pathways and provides substrates for DNA synthesis. Investigation of deamination of purine nucleotides in yeasts Candida guilliermondii NP-4 irradiated with X-rays, millimeter and decimeter electromagnetic waves, as well as after post-radiation incubation of cells has been realized. It has been shown that under the influence of X-ray and microwave irradiation in yeasts, the intensity of deamination of purine nucleotide-polyphosphates - ADP, ATP, GDF and GTP, has changed, which in all probability is an adaptive mechanism in the repair of yeasts after irradiation, provides the work of nucleotide salvage pathways, and can be associated with the metabolism of these compounds.

A preliminary evaluation of ATPase was performed in an experimental model of breast cancer. Total and mitochondrial ATPase activities were studied in the breast and liver of rats with DMBA-induced breast cancer. It has been shown that during the development of breast cancer in these tissues there is a significant increase in ATPase activity. At the same time, an increase in ATPase activity is seen in the liver of rats. In the case of treatment cancer rats with H.alpestre, there are almost no changes in ATPase activity in rats' liver homogenate and mitochondria compared to cancer animals. In the case of combined treatment with chemical inhibitors and H.alpestre, ATPase activity is significantly reduced with the use of L-NAME, the values obtained are lower even compared to healthy animals. However, with the use of nor-NOHA, a further increase in ATPase activity is observed. The obtained results will allow evaluation of the effectiveness of the therapeutic model by changing the energy balance, and selecting furthermore effective doses, to clarify the mechanisms of influence of these combination models.

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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 -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.