Catalytic properties of the membrane enzyme prostaglandin H synthetase in a system of inverted micelles of aerosol OT in octane

Prostaglandin H synthetase solubilized in octane with the aid of hydrated reversed micelles of Aerosol OT (AOT) exhibits a catalytic activity dependent on hydration of the surface-active substance and its concentration. The maximum rate of the reaction is attained at the H2O/AOT molar ratio equal to 20 and amounts to a value close to the one observed in an aqueous solution. The inactivation rate of the enzyme in the course of the reaction does not depend on the water content in the system and is described by a Kin value commensurable with the Kin in an aqueous solution.     

A new approach to titrating active enzyme centers upon the use of surface-active micellar substances in organic solvents

Micellar solutions of surfactant in organic solvents with rubber additions are proposed for determination of active enzyme concentration. A kinetic theory of enzymatic reactions in reversed micellar systems is developed, suggesting the intermicellar transport of the substrate to be the limiting step in viscous medium. Under these conditions, it is shown that fraction of the product formed after quick transformation of the substrate located in the enzyme-containing micelles depends upon active enzyme concentration and aggregation number of surfactant molecules. The proposed approach is used for the active-site titration of trypsin and cellobiase and for the determination of the aggregation number of Aerosol OT (AOT) molecules in the ternary system AOT/water/cyclohexane.     

Catalysis by enzymes entrapped into hydrated surfactant aggregates having lamellar or cylindrical (hexagonal) or ball-shaped (cubic) structure in organic solvents

Instead of aqueous solutions, universally recognized in enzymology, ternary systems of the water/organic solvent/surfactant type are suggested as liquid-crystalline media for enzymatic reactions. Two systems, water/octane/Aerosol OT and water/cyclohexane/Brij 96, have been used to solubilize acid and alkaline phosphatases and peroxidase. The enzymes under study do function in liquid-crystalline mesophases having lamellar, cylindrical (reversed hexagonal) and ball-shaped (reversed cubic) packing of the surfactant molecules. A significant result is that the phase transition from one liquid-crystalline structure to another entails, as a rule, a reversible change in the catalytic activity of the solubilized enzyme.     

Active centers of gamma-glutamyltransferase in the aerosol OT reverse micellar system in octane by an inhibitor analysis method]

Regulation of the supramolecular structure and catalytic activity of the heterodimeric enzyme gamma-glutamyltransferase in the system of Aerosol OT reversed micelles in octane was studied. Variation of the hydration degree causes a reversible dissociation of the enzyme to the light and heavy subunits, both possessing the catalytic activity. The subunits were separated on the preparative scale in the reversed micelle system using ultracentrifugation. The active centres of gamma-glutamyltransferase were studied using the enzyme's irreversible inhibitor AT-125 (L-(alpha S, 5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid). It is shown that the separation of the gamma-glutamyltransferase subunits results in "opening" of a new active centre in the heavy subunit, whereas in the enzyme's dimeric form this centre is masked and not accessible to the inhibitor's molecule. The kinetic and inhibitor analysis data indicate that the active centres in the light and heavy subunits are similar.     

Affinity sorbent based on tryptophyl-threonyl-tyrosine for binding of the immunoglobulins G: Sorption characteristics and aspects of practical application

Chromatographic material based on tryptophil-threonyl-tyrosine and efficiently binding human, sheep, goat, and bovine immunoglobulin G was obtained. High selectivity of the sorbent for extraction of immunoglobulins from blood plasma has been demonstrated. Effective sorption capacity is 15–25 mg of immunoglobulin G per 1 ml of the matrix. Optimization of the method of triptophyl-threonyl-tyrosine covalent binding to the polysaccharide matrix allowed the achievement of high sorbent stability in conditions of use and storage. This sorbent may be used in medicine and biotechnology.     

Structural organization of membrane and soluble forms of somatic angiotensin-converting enzyme.

The catalytic activity and quaternary structure of soluble (s) and membrane (m) forms of angiotensin-converting enzyme (ACE) were studied in reversed micelles of ternary system Aerosol OT--water--octane. The profile of the dependence of the catalytic activity of the two enzyme forms on the degree of surfactant hydration (micellar size) had several optima corresponding to the function of various active oligomeric enzyme forms; the curves for the s- and m-forms of ACE were different. Data of sedimentation analysis prove that in reversed micelles, s-ACE can exist as monomers, dimers, or tetramers depending on the hydration degree, and the m-form is present as dimers and tetramers only. The values of the kinetic parameters for the hydrolysis of the substrate furylacryloyl-Phe-Gly-Gly by all the enzyme forms were determined, and the data indicate that the activity of the m-form is enhanced by oligomerization. The ACE activity strongly depends on the medium; it is higher when ACE is in contact with matrix or other enzyme molecules.     

Artificial mountain climate in therapy and rehabilitation of patients with chronic nonspecific pulmonary diseases]

Therapeutic efficiency of artificial Alpine climate was studied in a group of 318 patients with chronic nonspecific pulmonary diseases (CNDP). The Alpine climate was modelled on device "Orotron". The base, progradient and prolonged regimes of therapy by artificial Alpine climate (orhotherapy) were used in work. It is shown that application of optimal conditions of orhotherapy promotes normalization of the external respiration function in patients with CNPD due to a decrease in expression of broncho-obstructive and bronchitic syndromes and in nonuniformity of regional ventilation of lungs. Therapy by artificial Alpine climate is recommended to be used in wide clinical practice for treatment and rehabilitation of patients with CNDP.     

Regulation of supermolecular organization and catalytic activity of the lysosomal complex GM1-galactosidase and neuraminidase in vitro

The regulation of the catalytic activity and supramolecular organization of human kidney Gm1-galactosidase and neuraminidase was investigated in the reversed micellar systems of Aerosol OT in octane. It was found that in the reversed micellar systems the Gm1-galactosidase can exist in the monomeric, tetrameric or octameric forms depending on the H2O/surfactant ratio in the system which determines the micelle size. The association of Gm1-galactosidase monomers into octameric structure characteristic of Gm1-galactosidase in the lysosomes results in a two fold increase of the specific catalytic activity of the enzyme. 32 kDa "protective" protein--the component of Gm1-galactosidase--neuraminidase native complex was found to improve significantly this association.     

Calculation of the shock Hugoniot of deuterium at pressures above 1 Mbar by the path-integral Monte Carlo method

Plasma Physics Reports - The shock Hugoniot of deuterium at pressures above 1 Mbar is calculated by the path-integral Monte Carlo method without introducing additional physical assumptions and...