Enzyme-polyelectrolyte noncovalent complexes as catalysts for reactions in binary mixtures of polar organic solvents with water

Abstract

The formation of non-covalent complexes with polyelectrolytes has been suggested to enhance the resistance of enzymes towards inactivation by organic solvents in their homogeneous mixtures with water. Existence of such complexes in water-cosolvent media was proved by experiments with a fluorescence dye, eosin. In the case of catalysis by (x-chymotrypsin, formation of the complex with polyelectrolytes produced two major effects: i) considerable increase in enzyme activity at concentrations of ethanol and N,N-dimethylformamide of 10-30 % v/v; ii) conservation of the enzymatic activity at cosolvent concentrations of more than 40 % v/v, where the native enzyme is completely inactive. General character of the observed activation and ~tabflization phenomena was shown by example of several experimental systems.

Increase of electrical properties using a novel mixed buffer system in an enzyme fuel cell

“…In addition, phosphate buffer salts which are small with proton donating and accepting groups in close proximity can simultaneously donate and accept protons [24]. MP-11 activity seemed to be improved by MOPS, because it reported that both the stabilization and activation of MP-11 effects were observed when MOPS buffer used [25]. For the high oxidation reaction of bioelectrical cell, the immobilized redox enzyme should have not only a good activity, but also the cell should have a good electron transfer through its buffer electrolyte.…”

Determination of Cyclosporin A in 20% Ethanol by a Magnetic Beads-Based Immunofluorescence Assay

“…To destroy hydrophobic complexes of CsA with serum albumins and to extract the drug from the surface of blood cells, a several-fold excess of 96.6% ethanol has to be added to a specimen. Since free proteins are known to denature in water-organic mixtures at relatively low concentrations of organic cosolvents (10 -40% (v/v), depending on the protein and cosolvent nature (27,28)), conventional methods of CsA immunoassay require many-fold dilution of the ethanol extract with aqueous buffer solution, which unfavorably changes the detection limit of the assay. Thus, while developing a method for CsA determination, it was first necessary to find the maximal concentration of ethanol which does not greatly affect the ability of antibodies to bind antigen.…”

Tyrosinase: Polybrene noncovalent complexes in water‐ethanol mixtures

“…A number of approaches directed toward better adaptation of enzyme to water-cosolvent mixtures have been put forward (Mozhaev et al, 1990). Formation of noncovalent enzyme-polyelectrolyte complexes has been suggested as a new approach to obtain biocatalyst with enhanced resistance toward inactivation by organic solvent (Gladilin et al, 1995). The protein-polycation com-plexes are spontaneously formed in aqueous solutions, mainly due to multiple electrostatic interactions between positive charges in the polycations and negatively charged carboxylic groups in the protein molecules.…”

“…These interactions may lead to an even stronger electrostatic binding of a protein to a polyelectrolyte in organic solvents due to the lower dielectric constant of the medium. It is assumed that this binding may be responsible for a higher stability of the enzyme in the complex with the polyelectrolyte against denaturation by the organic solvent (Gladilin et al, 1995).…”

“…In this work the catalytic activity of tyrosinase in complexes with a polycation was studied in homogeneous binary water-ethanol mixtures. As a cationic polyelectrolyte, polybrene, poly (1,5-dimethyl-1,5-diazaundecamethyelene) bromide (PB) was used, since the existence of catalytically active in water-cosolvent mixtures complexes of PB with a number of enzymes has been previously demonstrated (Gladilin et al, 1995). Tyrosinase was selected due to its numerous applications in bioanalysis of highly toxic environmental pollutants represented by a wide class of phenolic and polyphenolic compounds (Lie et al, 1999).…”