[Highly effective test-system for determination of the total antioxidant activity of human blood serum].

A highly effective test-system for quantitative characterization of the total antioxidant activity (TAA) of human blood serum (HBS), including methemalbumin (MetHa) as biocatalyst, H2O2 as the oxidant, o-phenylenediamine (PDA) as the acceptor of radicals and 2,2,5,7,8-pentamethylchroman-6-ol (PMC) as the inhibitor-calibrator, has been developed and proved under the laboratory environments. The test-system has been optimized for the concentrations of all the components, the reaction conditions and the PDA consumption monitoring at 37 degrees C in the medium of buffered physiological solution, pH 7.4 containing 5% DMFA and 0.

[Substituted aminophenols and flavonoids as potential components for test-systems of total antioxidant activity].

A comparative kinetic study of ortho-phenylenediamine (PDA) oxidation in the "pseudoperoxidase" system Methemalbumin-H2O2 in the presence of 2-amino-4-tret-butylphenol (ATBP), 2-amino-4,6-di-tret-butylphenol (ADTBP) and its four N-acyl derivates, as well as flavonoids (quercetin, morin, silibin, hesperidin and naringin) has been carried out under standart conditions at 20 degrees C in phosphate buffered saline, pH 7.4, containing 5.25% ethanol and DMFA.

[Role of fructose-1-phosphate kinase in expression of PEP-synthase in Escherichia coli K-12].

Mutational damage of the fruK gene coding for fructose-1-phosphate kinase leads to 2-6-fold (depending on the strain) decrease in FEP synthase activity in Escherichia coli. The fruK mutants were unable to utilize lactate as well as fructose and fructose-1-phosphate, acquiring, in addition, sensitivity to mannose in their growth medium. Reversions back to FruK+ phenotype or introduction of an intact fruK allele resulted in restoration of both FEP synthase activity and the ability to grow on lactate.

[Uncoupling expression of genes coding for the synthesis of proteins involved in transport and utilization of fructose in Escherichia coli K-12].

A novel mutation fruS localised in the fru operon has been obtained. The mutation uncouples expression of genes determining fructose specific uptake and utilization. In the fruS bacteria fruA and fruF genes (coding for enzyme II and FPr, respectively) become constitutive, while the fruK gene (responsible for fructose-1-phosphate kinase synthesis) remains inducible.