Перегляд за Автор "Gonchar, Mykhailo"

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Novel arginine deiminase-based method to assay L-arginine in beverages
(2016) Stasyuk, N.; Gayda, G.; Fayura, Lyubov; Boretskyy, Yuriy; Gonchar, Mykhailo; Sibirny, Andriy; Борецький, Юрій
A highly selective and sensitive enzymatic method for the quantitative determination of L-arginine (Arg) has been developed. The method is based on the use of recombinant bacterial arginine deiminase (ADI) isolated from the cells of a recombinant strain Escherichia coli and o-phthalaldehyde (OPA) as a chemical reagent. Ammonia, the product of the enzymatic digestion of Arg by ADI, reacts with OPA and forms in the presence of sulfite a product, which can be detected by spectrophotometry (S) and fluorometry (F). The linear concentration range for Arg assay in the final reaction mixture varies for ADI-OPA-F variant of the method from 0.35 lM to 24lM with the detection limit of 0.25 lM. For ADI-OPA-S variant of the assay, the linearity varies from 0.7 lM to 50 lM with the detection limit of 0.55 lM. The new method was tested on real samples of wines and juices. A high correlation (R = 0.978) was shown for the results obtained with the proposed and the reference enzymatic method.
Recombinant arginine-degrading enzymes in metabolic anticancer therapy and bioanalytics
(2015) Stasyk, Oleh; Boretsky, Yuriy; Gonchar, Mykhailo; Sibirny, Andriy
Tumor cells often exhibit specific metabolic defects due to the aberrations in oncogene-dependent regulatory and/or signaling pathways that distinguish them from normal cells. Among others, many malignant cells are deficient in biosynthesis of certain amino acids and concomitantly exhibit elevated sensitivity to deprivation of these amino acids. Although the underlying causes of such metabolic changes are still not fully understood, this feature of malignant cells is exploited in metabolic enzymotherapies based on single amino acid, e.g., arginine, deprivation. To achieve efficient arginine depletion in vivo, two recombinant enzymes, bacterial arginine deiminase and human arginase I have been evaluated and are undergoing further development. This review is aimed to summarize the current knowledge on the application of arginine-degrading enzymes as anticancer agents and as bioanalytical tools for arginine assays. The problems that have to be solved to optimize this therapy for clinical application are discussed.