[Effect of levorin on the intracellular pool of free amino acids in Ehrlich ascites carcinoma cells]. / Vliianie levorina na vnutrikletochnyi fond svobodnykh aminokislot v kletkakh astsitnoi kartsinomy Erlikha.

Levorene, a polyenic antibiotic, lowered the concentration of amino acids in the cells of Ehrlich carcinoma. The decrease in the intracellular level of the amino acids was due not only to inhibition of their entrance to the cells but also to their increased leaching from the cells. The effect of levorene on the intracellular level of the neutral amino acids was higher than that on the main amino acids which was associated with different sensitivity of the amino acid transport systems to the antibiotic.

[Heterogeniety of the amino acid pool for protein synthesis in Ehrlich ascites carcinoma cells]. / Geterogennost' fonda aminokislot dlia sinteza belka v kletkakh astsitnoi kartsinomy Erlikha.

Using a new methodological approach based on a step-wise labelling with [14C] and [3H] amino acids, it was demonstrated that the Ehrlich ascite carcinoma cells are capable of utilizing both intracellular and extracellular amino acid pools for protein synthesis. The inhibition of amino acid transport into the cells is accompanied by a more intensive utilization of the exogenous pool. The described procedure permits to calculate the specific radioactivity of the tRNA-bound amino acid and the absolute rate of protein synthesis.

[Effect of levorin on RNA synthesis in Ehrlich ascites carcinoma cells]. / Vliianie levorina na sintez RNK v kletkakh astsitnogo raka Erlikha.

The polyene antibiotic levorin had no effect on the incorporation of 14C-uracil into the pool of intracellular free nucleotides in Ehrlich ascites tumour cells. RNA synthesis was inhibited by the antibiotic only at the late stages of incubation, evidently, due to earlier disturbances of the protein synthesis and in cell energetics.

[Action of levorin on the incorporation of labelled amino acids into the proteins of Ehrlich ascitic cancer cells]. / Deistvie levorina na vkliuchenie mechenykh aminokislot v belki kletok astsitnogo raka Erlikha.

A polyenic antibiotic levorin had a significant damaging effect on the amino acid transport in the cells of Ehrlich's ascites carcinoma by inhibiting the incorporation and increasing the release of 14C-glycine and 14C-arginine. Inhibiton of incorporation of the radioactive amino acids into protein was observed on both simultaneous addition of the antibiotic and the label into the medium and addition of previously labeled cells into radioinactive medium with the antibiotic. Since in the latter case levorin had probably no effect on the specific radioactivity of the precursor, it was suggested that the decrease in the label incorporation into protein was an evidence of the real antibiotic inhibition of the rate of the synthesis of the polypeptide chain.

[Effect of levorin on the activity of facilitated diffusion systems in murine Ehrlich cancer cells]. / Deistvie levorina na aktivnost' nekotorykh sistem oblegchennoi diffuzii v kletkakh myshinogo raka Erlikha.

Five-minute incubation of the cells of Ehrlich's mouse carcinoma with levorin in a concentration of 0.25 microgram/ml resulted in a release of 30% of K+ and 40-50% suppression of active transport of neutral amino acids. No changes in incorporation of nitrous compounds, nucleosides and cyclophosphamide, an antitumor drug transported by the systems of facilitated diffusion were observed under the same conditions.