Isolation, purification, and characterization of nitrate reductase from a salt-tolerant Rhodotorula glutinis yeast strain grown in the presence of tungsten.

The salt-tolerant Rhodotorula glutinis yeast strain grew in medium containing nitrate, 1 mM tungsten, and trace amounts of molybdenum (as impurities from the reagents used). Isolation of electrophoretically homogenous preparation of nitrate reductase from the Rh. glutinis cells grown under these growth conditions is described.

[Properties of nitrate reductase from Fusarium oxysporum 11dn1 fungi grown under aerobic and anaerobic conditions].

Production of nitrate reductase was studied in 15 species of microscopic fungi grown on a nitrate-containing medium. Experiments were performed with Fusarium oxysporum 11dn1, a fungus capable of producing nitrous oxide as the end product of denitrification. Moreover, a shift from aerobic to anaerobic conditions of growth was accompanied by a sharp increase in the activity of nitrate reductase.

Tungsten-containing enzymes.

The biological importance of tungsten has been fully proved in the last decade due to isolation of a number of tungsten-containing enzymes (W-enzymes) from hyperthermophilic archaea. Tungsten was previously considered only as an antagonist of molybdenum, because the replacement of molybdenum by tungsten (due to their chemical similarity) leads to inactivation of molybdenum-containing enzymes (Mo-enzymes). In addition to the "true W-enzymes" in which tungsten cannot be replaced by molybdenum, recently some enzymes have been isolated which can use either molybdenum or tungsten in the catalytic process.

[Kinetic method of tungsten analysis in tungsten-containing enzymes].

A highly sensitive method for tungsten detection in proteins based on the ability of this metal to catalyze the oxidation of with hydrogen peroxide is described. The method allows determining tungsten in protein samples in the concentration range of -0.05 to -0.