[L-arginine assay with the use of arginase I].

A highly selective and sensitive method for the quantitative determination of L-arginine (Arg) with a fluorescent detection of the reaction product has been developed. The method is based on the use of human liver arginase I isolated from a recombinant producer strain, yeast Hansenula polymorpha, and 2,3-butanedione monoxime, which is used to detect carbamide--the product of enzymatic reactions. The linear concentration range for determining Arg in the final reaction mixture varies from 0.

[Human arginase I from the recombinant yeast Hansenula polymorpha: isolation and characterization of the enzyme].

Purified human arginase I preparations homogeneous in SDS-PAAG test were obtained by the affinity chromatography on the synthesized sorbent L-arginine-macroporous glass. Some physico-chemical characteristics of the isolated arginase preparation have been estimated: thermo- and pH-stability, temperature- and pH-optima of the enzyme. The influence of some bivalent metal ions and other additives on enzymatic activity for stabilization of the enzyme and optimization of its storage conditions was studied.

[Screening of yeasts producing stable L-lactate cytochrome c oxidoreductase and regulation of enzyme synthesis].

Screening of strains producing a stable form of L-lactate cytochrome c oxidoreductase (flavocytochrome b2, FC b2) was carried out among 14 yeast species. Enzyme activity was detected in polyacrylamide gel after the electrophoresis of cell-free extracts. The FC b2 of Hansenula polymorpha, Rhodotorula pilimanae, and Kluyveromyces lactis are characterized by high thermostability; in particular, the FC b2 of H.