[Effect of ionic composition of incubation medium on inhibition by levorin of amino acid transfer in Candida albicans]. / Vliianie ionnogo sostava sredy na tormozhenie levorinom transports aminokislot u Candida albicans.

It was demonstrated that K+ and Na+ concentrations in C. albicans cells cultivated on an aerated enriched complex medium do not practically depend on their concentration ratios in the medium. The effect of levorin on the ionic composition of the cells, on the contrary, strongly depends on the composition of the medium. In a Na-containing medium with levorin the bulk of intracellular potassium is substituted by sodium, while in a "potassium" medium no redistribution of the monovalent cations in the cells occurs. The transport of neutral amino acids with a short carbohydrate radical (e. g. glycine, alanine) is largely inhibited by levorin irrespective of the intra- and extracellular concentrations of the movement cations. The inhibition of transport of amino acids with a long carbohydrate radical (e. g. leucine, phenylalanine) by levorin is possibly mediated by its effect on the intracellular concentration of monovalent cations, since in "potassium" medium it is either insignificant or altogether absent. The transfer of neutral amino acids differing in the length of the carbohydrate radical of C. albicans by various systems is discussed.

[Effect of levorin on incorporation of individual amino acids into proteins of membranes, ribosomes and cell sap of Candida albicans]. / Deistvie levorina na vkliuchenie individual'nykh aminokislot v belki membran, ribosom i kletochnogo soka Candida albicans.

The effect of levorin on incorporation of labelled amino acids into the protoplasts and proteins of C. albicans depended on the ionic composition of the medium and on the amino acid tested. In a potassium-enriched medium the predominant effect of levorin on [14C] alanine transport into the protoplasts was decreased, while in case of [14C] leucine transport it was completely eliminated. The incorporation of [14C] alanine into the proteins of ribosomes and cell juice was inhibited by the antibiotic in a greater degree as compared to the membrane proteins, the difference in the rate being more pronounced in a sodium-enriched medium. The incorporation of [14C] leucine was inhibited in all protein fractions in the same degree, which was observed only in a sodium-enriched medium.

[Action of levorin on amino acid transport in Candida albicans]. / Deistvie levorina na transport aminokislot u Candida albicans.

It was shown that suppression by levorin of the leucine transport into the cells of C. albicans was due to replacement of intracellular K+ by Na+ induced by the antibiotic. The alanine transport was suppressed by levorin irrespective of the ratio of the monovalent cations concentration in the medium and inside the cell. The levorin effect on the protone escape from the cells was negligible and probably played no significant role in the mechanism of the amino acid transport suppression by the antibiotic.

[Effect of amigluracil and levorin on membrane permeability and protein synthesis in Candida albicans protoplasts]. / Vliianie amigluratsila i levorina na membrannuiu pronitsaemost' i sintez belka v protoplastakh Candida albicans.

It was shown that amigluracyl, a water soluble derivative of methacyl which decreased the nephrotoxic effect of polyens activated the membrane permeability in Candida albicans for a mixture of 14C-amino acids but had no significant effect on protein synthesis in this microorganism. The level of inhibition of the membrane permeability in C. albicans for the amino acids and protein synthesis in the fungus by levorin did not practically depend on the presence of amigluracyl in the incubation medium. The minimum levorin concentration inhibiting the growth of Candida albicans in the presence or absence of levorin was 0.039 gamma/ml. Therefore, amigluracyl may be used in combination with polyenic antibiotics for the treatment of mycoses.

[Dependence of inhibition by levorin of amino acid incorporation into protoplasts and subcellular proteins of Candida albicans on the change of endocellular potassium concentration]. / Zavisimost' tormozheniia levorinom vkliucheniia aminokislot protoplasty i belki subkletochnykh fraktsii Candida albicans ot izmeneniia vnutrikletochnoi kontsentratsii kaliia.

Levorin is found to decrease more efficiently potassium concentration in C. albicans protoplasts under their incubation in the presence of sodium than in the medium containing the equivalent amount of potassium. Minimal inhibitory concentration of levorin for resistant C. albicans cells incubated on potassium-depeleted medium was in 4 times lower than for cells incubated in potassium-enriched medium. The decrease of membrane permeability for 14C-amino acids and their incorporation into membrane, ribosomal and soluble proteins under the effect of levorin was more pronounced when protoplasts were cultivated in sodium-containing medium than in potassium-containing one. In both media the inhibition of 14C-amino acid incorporation by levorin into ribosomal and cytosol proteins was more efficient than into membrane proteins, but these differences were less pronounced in case of potassium-containing medium.