Properties of conformation-out-equilibrium states of several iron containing proteins, for example, induced by fast changes of active site were investigated. It was shown that structure and chemical properties of out-of-equilbrium states can differ considerably from the equilibrium ones. Spectral characteristics and reactional ability of these molecules change in the way of slow (up to 10(-1)s) conformational relaxation, continuously approaching the equilibrium values.

Binding Sites↗

PubMedDate not supplied

[Conformation of cytochrome c, adsorbed on different substrates].

Visible spectra of cytochrome c adsorbed on solid supports and on the same supports covered with monolayers of lecithin and cholesterol were studied. It was shown that absorption spectra of high spin cytochrome c and pK of transition from low to high spin form depend on the nature of adsorbent surface.

Adsorption↗

PubMedDate not supplied

[Low temperature reduction of cytochrome c complexes].

The absorption spectra of ferricytochrome c complexes with azide, imidazole and cyanide reduced by trapped electrons at the liquid nitrogen temperature were investigated. Differences have been found between the absorption spectra at T=77 degrees K of cytochrome c complexes reduced by radiation and the absorption spectrum of ferrocytochrome c. These differences are supposed to be due to the axial ligation of the Fe(II) by exogenous ligand. The temperature increase led to the removal of exogenous ligand from Fe(II).

Azides↗

PubMedDate not supplied

[Absorption and magnetic circular dichroism spectra of heme proteins in nonequilibrium states. IV. Cytochrome c and its derivatives].

Absorption and magnetic circular dichroism spectra (77 degrees K) of nonequilibrium cytochrome c and its derivatives reduced by thermolysed electrons was studied. The low temperature spectral characteristics of reduced cytochrome c (pH 7.0, 1.6 and 10.0), dimer, carboxymetylated and formylated derivatives at netral and acid pH, also fluoride complexes differ from the characteristics of equilibrium reduced forms. The temperature increase (up to 177 degrees K) induces relaxation of nonequilibrium states. These effects are due to structural differences in the heme vicinity of the reduced and oxidized forms.

Circular Dichroism↗

PubMedDate not supplied

[Comparative study of the kinetics of the reduction of cytochrome c and the nitroxide radical in reversed aerosol OT micelles in octane].

The comparison of the reduction kinetics of cytochrome c and nitroxide radical by ascorbate in reversed micelles of aerosol OT in octane was studied. The plot of the dependence of the reduction rate constant on the micelle hydratation is bell-shaped in the case of protein but shows the plateau form for the radical. The reaction rates decreases at high micelle concentrations. The equations have been drawn that connect the experimental rate constants with intramicellar biomolecular rate constant (km) for reagents unsolved in organic phase. In the case of strong hydratated micelles km for the radical reduction is practically equal to the rate constant in aqueous solution. For cytochrome c the ratio of these constants is less than 0.22, that may be explained by protein conformational changes detected by optical methods. For small micelle hydratation the dependence of the cytochrome reduction rate on ascorbate concentration is characterized by plateau. Under these conditions the limited stage of reaction is apparently the transition of the protein to the active conformation.

Animals↗

PubMedDate not supplied

[ESR-spectroscopy of cytochrome P-450 LM2 in the soluble and membrane-bound state].

Influence of microenvironment on the structure of spin-labeled cytochrome P-450 LM2 was studied. The distance between the spin-label which is covalently bound to cysteine-152 and heme ferrum in soluble protein is 17 A and 23 A in the membrane-bound one. The spin-label was exposed in water solution in both cases. It was shown that solubilized cytochrome P-450 LM2 in water solution forms the aggregates consisting of 4-6 monomers.

Cytochrome P-450 Enzyme System↗

PubMedDate not supplied

[The effect of reversed micelles of cetyltrimethylammonium bromide on equilibrium constants and kinetics of oxidation-reduction reactions with the participation of cytochrome c].

To model the effect of membrane environment on the electron transfer reactions we studied the thermodynamics and kinetics of the reactions of cytochrome c and 2,6-dichlorophenolindophenol with ferri- and ferrocyanide in the reversed micelles cetyltrimethylammonium bromide in chloroform/octan mixture. Incorporation of the protein in micelles leads to increasing the equilibrium constant (K1) up to 300 times. This effect is mainly due to a decrease in the ferrocytochrome c oxidation rate constant in the reaction with ferricyanide. Micellar solubilization of the dye also leads to a marked increase in the equilibrium constant K2. The estimations of the values K1 and K2 in water-alcohol mixtures and in aqueous micellar solutions of surfactant together with kinetical and spectral data show that the increase of K1 and K2 in reversed micelles is caused generally by redox potential changes of low-molecular reagents. The latter change their environment after adsorption on the micellar surface.

2,6-Dichloroindophenol↗

PubMedDate not supplied

[Effect of adsorption on the structure and properties of hemoglobin].

Adsorption spectra of Hb+ and HbO2 adsorbed on silica and monolayers cholesterol supported on silica have been studied. It is shown that immobilization leads to new states of proteins, their properties depending on the nature of support and conditions of adsorption. Adsorption of haemoglobin leads to its inactivation. The rate of inactivation decreases with an increase of surface concentration of haemoglobin and with simultaneous adsorption of inert proteins.

Adsorption↗

PubMedDate not supplied

[Reduction of cytochrome c adsorbed on liposomes].

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Adsorption↗

PubMedDate not supplied

[A study of the effect of solvent composition and viscosity on the molecular dynamics of human serum albumin using Rayleigh scattering of Mössbauer radiation].

By means of RSMR changes of human serum albumen intramolecular mobility by addition of 1.5% and 7.5% of glutar dialdehyde (GD) in concentrated protein solution, heat denaturation of a protein or substitution of water by water-glycerol solvent with amount of water to glycerol: 1 to 2 were studied. It is shown that the elastic fraction for HSA is changed much less addition of GD or by heat denaturation than by substitution of water solution by water-glycerol. It seems that the observed strong influence of glycerol on intramolecular mobility of HSA is connected mostly with effective dehydration of protein (by substitution of the part of a water solvent by glycerol) and with a small volume decrease of protein (due to preference hydration effect) rather than with the increase of the solvent viscosity.

Humans↗

PubMedDate not supplied

[Optical spectroscopy of methemoglobin from the Lampetra fluviatilis river lamprey and its complexes reduced at 77K].

The absorption spectra from met-haemoglobin from lamprey Lampetra fluviatilis and its complexes with F-, CN-, N3- and imidazole were studied in non-equilibrium states arising in low-temperature (77K) reduction of water-glycerol of oxidized forms of protein with thermolyzed electrons. The Soret band was shown to be not split in low-temperature absorption spectra of reduced met-haemoglobin and its complexes unlike that of the equilibrium deoxyhaemoglobin. It was concluded that met-haemoglobin has a higher symmetry of the active centre as compared to deoxyhaemoglobin.

Animals↗

PubMedDate not supplied

[Effect of lipids on CO recombination with ferrocytochrome P-450].

Using the flash photolysis technique the kinetics of recombination of carbon monoxide with ferrocytochrome P-450 LM-2 was investigated. Ferrocytochrome P-450 was incorporated into liposomes prepared from different lipids: from microsomal lipids, phosphatidylcholine from egg yolk, dipalmitoylphosphatidylcholine. It was found that the activity and structure of ferrocytochrome P-450 conformers is affected by the lipid microenvironment. The kinetics of the CO-binding is affected also by the nature of lipids.

Carbon Monoxide↗