S. V. Muginova

Ionic liquids in enzymatic catalysis and biochemical methods of analysis: Capabilities and prospects

The first Russian review systematizes and discusses the most important and promising published data on the use of ionic liquids in biocatalysis and, especially, biochemical methods of analysis. Studies on the use of ionic liquids as solvents for enzymes, new reaction media for enzymatic reactions, and components of the biosensitive layers of sensors are analyzed. The physical and chemical properties of ionic liquids used in biocatalysis are discussed. The advantages of ionic liquids over the usual solvents in homogeneous and heterogeneous reactions with the participation of enzymes from various classes are demonstrated, procedures for the coimmobilization of biocatalysts and ionic liquids with cellulose onto polymer supports and electrodes are described, and prospects for the use of enzyme-ionic liquid compositions in biochemical methods of analysis are considered.

Determination of organomercury compounds using immobilized peroxidase

Abstract The effect of organomercury compounds (methyl-, ethyl- and phenylmercury) on the activity of immobilized peroxidase was studied. Peroxidase was immobilized in chitosan films in wells on a polystyrene plate and on chromatography paper. The oxidation reactions of o -dianisidine, o -phenylenediamine and 3,3′, 5,5′-tetramethylbenzidine by H 2 O 2 were used as indicators. The rate of all the indicator reactions was monitored visually by measuring the time of appearance of the colour of the oxidation product. The liberating effect of organomercury compounds on peroxidase immobilized on both the above mentioned supports using o -dianisidine oxidation in the presence of the inhibitor phenylthiourea and the effect of organomercury compounds on the duration of an induction period of 3,3′, 5,5′-tetramethylbenzidine oxidation in the presence of diethyldithiocarbamate catalysed by paper-immobilized peroxidase were used for the development of enzymatic test procedures for the determination of organomercury compounds at concentrations of 0.02–1000 μM. The relative standard deviation ( n = 3) at the lower limits of their analytical concentration ranges in the proposed test procedures using o -dianisidine are 18–23% ( n = 3).

Applications of Ionic Liquids for the Development of Optical Chemical Sensors and Biosensors

This paper reviews the primary literature reporting the use of ionic liquids (ILs) in optical sensing technologies. The optical chemical sensors that have been developed with the assistance of ILs are classified according to the type of resultant material. Key aspects of applying ILs in such sensors are revealed and discussed. They include using ILs as solvents for the synthesis of sensor matrix materials; additives in polymer matrices; matrix materials; modifiers of the surfaces; and multifunctional sensor components. The operational principles, design, texture, and analytical characteristics of the offered sensors for determining CO2, O2, metal ions, CN-, and various organic compounds are critically discussed. The key advantages and disadvantages of using ILs in optical sensing technologies are defined. Finally, the applicability of the described materials for chemical analysis is evaluated, and possibilities for their further modernization are outlined.

Effect of Mercury(II) Traces on Catalytic Activity of Peanut and Horseradish Peroxidases

Abstract Mercury(II) in the range of 0.1–1 µg L−1 concentrations was found to be a much more efficient inhibitor of native peanut peroxidase (PNP) than of horseradish peroxidase (HRP) in the reaction of o‐dianisidine oxidation with hydrogen peroxide. The possible reason for the different degree of mercury(II) effects on the catalytic activity of both enzymes was studied. It was shown that the different number of glycans in PNP and HRP molecules (three and eight, respectively), or their absence in the molecule of wild‐type recombinant horseradish peroxidase refolded from E. coli inclusion bodies (recHRP), does not play a significant role in the effects caused by mercury(II). The efficient inhibition of PNP by mercury(II) in the absence of any other additives (for example, thiourea) originates from a greater mobility of the distal calcium ion in the enzyme molecule. A model scheme for the interaction of the studied plant peroxidases with mercury(II) was proposed. The PNP‐based enzymatic method for mercury(II) determination with c min =0.04 µg L−1 (0.2 nmol L−1) was developed and the possibility of PNP application for analysis of different samples was demonstrated.

Apoenzymes of Alkaline Phosphatases of Different Origin for Determining of Trace Zinc(II)

The applicability of the apoenzymes of three alkaline phosphatases of different origin (bacterial from E. coli and animal from chicken intestine or the small intestine of a Greenland seal) to the determination of zinc(II) was studied. The alkaline apophosphatase from seal intestine was found to be promising for this purpose. The preparation conditions of the apoenzyme and the conditions of its reactivation with zinc(II) were optimized. Based on the reactivating effect of zinc(II) on the apoenzyme, which was prepared with the use of EDTA, an enzymatic method was developed for determining zinc(II) (0.01–0.1 μg/mL) with cmin = 8 ng/mL. The proposed procedure was applied to the determination of zinc(II) in blood serum.

Enzymatic methods of analysis: Novel approaches and applications

The results of a series of investigations dealing with the development of enzymatic methods for determination of biologically active compounds, viz., inhibitors, activators, and substrates of native and immobilized enzymes of the oxidoreductase (peroxidases, alcohol dehydrogenases) and hydrolase (alkaline and acid phosphatases) classes isolated from diverse sources are summarized. Novel original approaches, proposed by the authors, for improving the sensitivity, selectivity, and rapidity of the methods are discussed. Numerous examples of application of the developed enzymatic procedures for the analysis of a wide range of samples are given.

Determination of Zinc(II) Using Native and Immobilized Alkaline Phosphatases of Different Origin

The effect of zinc(II) and other metal ions on the catalytic activity of native and immobilized alkaline phosphatases isolated from three different sources (Escherichia coli, chicken intestine, and small intestine of Greenland seal) was studied. Zinc(II) inhibits the catalytic activity of all native alkaline phosphatases to different extents. Zinc(II) produces the most significant and selective effect only on the alkaline phosphatase from seal intestine. As for alkaline phosphatases immobilized on polyurethane foam, zinc(II) hardly affects the activity of the enzyme from chicken intestine and inhibits the phosphatases from E. coli and seal intestine in concentrations from 2.5 to 50 μg/mL and 0.1 ng/mL to 50 μg/mL, respectively. With the use of native and immobilized alkaline phosphatase from the small intestine of the seal, selective procedures were developed for the determination of Zn(II) with spectrophotometric and visual control of the reaction rate. The detection limits are 1 μg/mL and 0.1 ng/mL, respectively.

Enzymatic Methods for the Determination of Mercury(II)

Enzymatic methods for the determination of mercury(II) using native and immobilized enzymes from different classes and sources were considered. Enzymatic procedures were compared in sensitivity, selectivity, rapidity, and experimental techniques. The main approaches to controlling the performance characteristics of the enzymatic procedures were discussed. The application of these procedures to the determination of mercury(II) in particular samples (water and soils of different origin and biological fluids) was considered.

The effect of the nature of hydrophilic ionic liquid on the catalytic activity of horseradish and soybean peroxidases

The kinetics of guaiacol oxidation by hydrogen peroxide and tert-butyl hydroperoxide catalyzed by horseradish and soybean peroxidases in the presence of 1-butyl-3-methylimidazolium acetate and tet-rafluoroborates of 1-butyl-3-methylimidazolium and N-butyl-4-methylpyridinium are studied and compared. The inhibiting effect of acetate ionic liquid on both peroxidases that occurred via the noncompetitive type is found; the Michaelis and inhibition constants have been calculated. Causes of different degrees of inhibition of the catalytic activity of plant peroxidases by ionic liquids are discussed. The advantages of their application compared to the polar molecular organic solvents are demonstrated.

Enzymatic Method for Heavy Metals Determination in Waters and Soils

The determination of heavy metals traces has an increasing importance in environmental analysis. Instrumental methods for heavy metals determination are highly sensitive and selective, but most of them are fairly complicated and require using specialized and expensive equipment. Enzymatic methods are characterized by simple device, experimental techniques and extremely proposing for environmental monitoring.