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Biomedical subjects

A I Kotel'nikov

Publications and source records attributed to A I Kotel'nikov.

18 recordsLinked to original sources
PubMed2006

Reactions of sulfur-nitrosyl iron complexes of "g=2.03" family with hemoglobin (Hb): kinetics of Hb-NO formation in aqueous solutions.

NO-donating ability of nitrosyl [Fe-S] complexes, namely, mononuclear dinitrosyl complexes of anionic type [Fe(S2O3)2(NO)2]-(I) and neutral [Fe2(SL1)2(NO)2] with L1=1H-1,2,4-triazole-3-yl (II); tetranitrosyl binuclear neutral complexes [Fe2(SL2)2(NO)4] with L2=5-amino-1,2,4-triazole-3-yl (III); 1-methyl-1H-tetrazole-5-yl (IV); imidazole-2-yl (V) and 1-methyl-imidazole-2-yl (VI) has been studied. In addition, Roussin's "red salt" Na2[Fe2S2(NO)4] x 8H2O (VII) and Na2[Fe(CN)5NO] x H2O (VIII) have been investigated. The method for research has been based on the formation of Hb-NO adduct upon the interaction of hemoglobin with NO generated by complexes I-VIII in aqueous solutions. Kinetics of NO formation was studied by registration of absorption spectra of the reaction systems containing Hb and the complex under study. For determination of HbNO concentration, the experimental absorption spectra were processed during the reaction using standard program MATHCAD to determine the contribution of individual Hb and HbNO spectra in each spectrum. The reaction rate constants were obtained by analyzing kinetic dependence of Hb interaction with NO donors under study. All kinetic dependences for complexes I-VI were shown to be described well in the frame of formalism of pseudo first-order reactions. The effective first-order rate constants for the studied reactions have been determined. As follows from the values of rate constants, the rate of interaction of sulfur-nitrosyl iron complexes (I-VI) with Hb is limited by the stage of NO release in the solution.

Hemoglobins↗
PubMedDate not supplied

[Study of sarcoplasmic reticulum Ca-ATPase by the paramagnetic label--paramagnetic probe method].

ESR spectra of nitroxyl derivative labelling with parachlormercury benzoate bound with SH-groups of Ca, Mg-dependent ATPase in the presence of Mn2+ ions are studied. It has been concluded from the saturation curves of ESR spectra that Mn2+ is localized at the distance approximately 40 A from the SH-group of the enzyme active centre. Platinum compound (K2PtCl4) changes the spectrum of ESR 1 due to the displacement of the label from the enzyme SH-groups and disintegration of the sarcoplasmic reticulum structure. Palladium compound (Pd(NH3)4Cl2) produced no effect on the ESR 1 spectrum.

Animals↗
PubMedDate not supplied

[Study of catalytically active center of the Ca2+-Mg2+-dependent ATPase of sarcoplasmic reticulum by triplet probe method].

It was shown that eosine and erythrosine are competing inhibitors of the Ca2+-Mg2+- dependent ATPase active center of sarcoplasmic reticulum. The eosine and erythrosine inhibition constants are equal to 1.4 x 10(-6) M and 1.1 x 10(-6) M, respectively. Nitroxide radicals of various hydrophobicity and K3Fe(CN)6 were used to compare the constants of triplet states exchange quenching of erythrosine in aqueous solution, in lecithine liposomes and in ATPase active center of sarcoplasmic reticulum. It was established that ATPase binding center was immersed into a liquid phase and was not connected with lipids. Mn2+ and Gd3+-ions, which are competing with Mg2+ and Ca2+ for binding sites in the enzyme active center, diminished the phosphorescence quenching time of eosine at 77K. This means that the ion binding sites are less than 12 A apart from ATP-binding center.

Animals↗
PubMedDate not supplied

[Structure and intramolecular dynamics of a photoactive pigment-protein eosin-casein complex].

The structure of eosin--casein complex was studied by triplet label method. Quantitative data on the quantum--mechanic exchange interaction between eosin centres and external quenchers were obtained. The dynamic state of water--protein matrix at -20 degrees to -180 degrees C with eosin as fluorescence and phosphorescence labels and natural chromophores of protein--tryptophane was studied.

Caseins↗
PubMedDate not supplied

[Reaction kinetics of electron phototransfer in an eosin-casein complex].

The role of protein matrix in the process of charge photorespiration on the model of eosin-casein complex was studied. We have also studied the kinetics of the electron transfer reactions being photosensitized by free eosin and eosin sorbed on casein in the donor (cystein) - acceptor (methylviologen) system. When eosin is sorbed on protein a 10-fold increase of the probability relation of non-retrospective direct electron transfer to the restrospective one was observed.

Caseins↗
PubMedDate not supplied

[Use of triplet state exchange disactivation phenomenon for the study of structure and electron conductivity of proteins].

A method for studying protein structure and estimating its electron conducting properties is proposed. The method is based on the kinetic recording of exchange quenching triplet labels and probes phosphorescence by chromophores or paramagnetic centres. It is shown that different types of exchange interactions (spin exchange, exchange energy transfer) between centres with distance R are described approximately by an equation (I = I0 exp-2R/L) where L changes from 0.7 A (absence of electron coupling--system of type I) to 6.5 A (strong electron coupling--system of type II). I (sec-1) corresponds to exchange energy transfer rate constant or exchange integral in the case of spin exchange. Life-times of excited triplet state eosin-isotiocionate labels connected with the terminal NH2-groups of the following preparations were measured by the method of kinetic phosphorescence decay recording: human oxyhemoglobin, methemoglobin, F- and CN-methemoglobin, metmyoglobin, F- and CN-metmyoglobins. The influence of lysozyme of the nitroxyl spin label bound to His-15 group on the phosphorescence spectrum was investigated. The analysis of our and literature data on the exchange interactions between the centres localized on the protein with known structure (hemoglobin, myoglobin, lysozyme, carboangidrase, bacterial ferredoxin) permit us to conclude that in the examined cases the experimental values correspond to model systems of type I and are different from the dependence in systems of type II by 5--15 order. This allows us to use equation (I) for estimation of the distances between the centres on proteins.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[Fluctuational intramolecular mobility of proteins using physical labels].

An analysis of spin,- fluorescence, triplet- and Mössbauer labeling techniques is given as well as the method of radical pair recombination for investigation of globular proteins molecular dynamics in the temperature range of 50-300 K and correlation time tau c = 10(-2) - 10(11) s-1. Based on experimental evidence and literature data a conclusion is drawn on the existence of protein microheterogeneity at negative temperatures. A dynamic model of a globular protein is proposed. It is supposed to be a system of tightly-packed polypeptide proteins blocks connected by hinge-like linkage with a few degrees of freedom. The system is sunk in viscous amorphous medium composed of superficial protein groups and bound water molecules. The correlation between the protein molecular dynamics and enzymes activities is discussed.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[Intramolecular dynamics and electron transfer in photosynthetic reaction centers. A study using luminescence].

The temperature dependences of fluorescence and phosphorescence spectra maxima of chromophor labels--endogenic (tryptophan) and exogenic (eosinisothiocyanate)--were measured for the preparations of photosynthetic membranes and reaction centers from Rhodospirillum rubrum. It was found that the dipole mobility of protein-lipid matrix in the vicinity of the chromophores intensified markedly with a temperature rise from 150 to 300K resulting in the corresponding relaxation time tau r decrease from 10(0) to 10(-8) s. The efficiency of direct transfer of the photomobilized electron in the system of quinone acceptors (A1- leads to A2) of reaction centers (characteristic half-times of the process being 10(-3) divided by 10(-4) s) was shown also to increase sharply at temperatures higher than 200K parallel to the enhancement of molecular motions with tau r approximately 10(-8) s. Meanwhile, changes observed in the rate of recombination of primary photoproducts, i.e. an oxidized bacteriochlorophyll dimer, P+ and a reduced acceptor, A1- (characteristic half-time of 10(-1) divided by 10(-2) s) and the activization of low-frequency motions with tau r approximately 10(-3) s in the external layers and tau r less than 1 s in the internal parts of the reaction centers protein develop over the same range of low temperatures (150-220 K). The nature of interactions which determine the dependence of the photosynthetic electron transport on the molecular mobility of the membrane proteins is discussed.

Bacterial Proteins↗
PubMedDate not supplied

[The use of the annihilated delayed fluorescence phenomenon in the study of the structural organization of the sarcoplasmic reticulum].

Self-interaction of triplet-excited probes and interaction between the triplet-excited probes and a quencher (ferrocene) at 30 degrees C have been studied in Sarcoplasmic reticulum membranes (SR) and in dimiristoyl phosphatidylcholine liposomes by means of annihilated delayed fluorescence (ADF) registration. Perylene, 7,12-dimethyl benzanthracene and 4-(2-anthryl) butanoic acid have been used as triplet probes. An average time decay ADF of perylene and 4-(2-anthryl) butanoic acid in SR is equal to 4,2: 10(-5) s and 2,3 X 10(-5) s, respectively. Triplet states constant quenching of perylene by ferrocene is equal to 2,1 X 10(7) (mM/g of lipids)-1 X s-1 in SR and 4,5 X 10(7) (mM/g of lipids)-1 X s-1 in liposomes. This means that lipids in a liquid crystalline phase form continuous extended regions containing more than 7 X 10(3) lipid molecules and free of significant hindrances in probes diffusion.

Chemical Phenomena↗
PubMedDate not supplied

[Investigation of model and biological membranes by probes emitting annihilated delayed fluorescence].

Registration of the annihilated delayed fluorescence kinetics of anthracene, 1,2-benzanthracene, 1,2,5,6-dibenzanthracene, 7,12-dimethylbenzanthracene, pyrene, 1,2-benzpyrene, 3,4-benzpyrene, perylene, and other aromatic compounds under laser excitation permitted investigation of the quenching of excited triplet molecules by hydrophobic quenchers (ferrocene, nitroxide radicals). A long life-time of the triplet excited states (10(-4)-10(-5) s) makes it possible to investigate the probe-quencher interactions in liposome and natural membranes at the probe concentration of 10(-6)-10(-7) M and the ratio of quencher/lipid = = 10(-4). The method enables to investigate localization of the enzyme active centre (hemes, non-heme iron, flavine) and lipid matrix organization in the lipid-protein complexes.

Fluorescent Dyes↗
PubMedDate not supplied

[Application of phosphorescent probes in investigations of model and biological membranes].

Possibility of using phosphorescent probes for membrane investigations was analysed on lecithin liposomes and rat liver microsomes taken as an example. It was shown that one quencher molecule on 10(4) lecithin molecules is sufficient for experimental registration of diffusion-controlled quenching of erythrosine phosphorescence by stable nitroxide radicals. It is possible to study the diffusion processes with D = 10(-5) divided by 10(-9) cm2s-1. Application of quenchers of different polarity allows to make a conclusion that the phosphorescent probe erythrosine is localized in liposomes in the region of polar heads of phosphatidyl choline. It was determined from the rate of phosphorescence quenching by radicals that the membrane microviscosity in this region at 20 degrees C equals approximately 1 puas. The coefficient of erythrosine lateral diffusion in liposomes estimated from their self-quenching equals 1,1 x 10(-8) cm2s-1. In the microsome erythrosine is localized in hydrophobic parts of proteins and is not accessible for the quencher molecules.

Animals↗
PubMedDate not supplied

[Analysis of experimental data on kinetics of electron transfer in metal-containing proteins and within the framework of an adiabatic approach].

Conception of the microsecond intramolecular protein dynamics with wide distribution of relaxation times is used for interpretation of published data on electron transfer kinetics in natural and chemically modified proteins. This is the evidence not only the unit static structure, but the dynamical organization of proteins as high organized molecular systems.

Electrons↗
PubMedDate not supplied

[Effect of molecular dynamics on the photoinduced electron transfer in eosin-myoglobin complex].

The temperature dependence of the rate constant of photoinduced electron transfer in the modified eosin-myoglobin complex by monitoring of the phosphorescence quenching of eosin is measured. The values of electron transfer rate constants are equal 10(2) + 10(3) s-1 in the temperature region 150-200 K. The kinetics of relaxation of the maximum of the time-resolved phosphorescence spectra of eosin on apomyoglobin is measured in the same temperature range. The solvation relaxation of the time-resolved phosphorescence spectra is nonexponential. The characteristic times of the solvation relaxation are given 10(-2) + 10(-4) s-1, that correlate with the time of electron transfer in this system. It was observed the "acceleration" of the relaxation rate of the time-resolved phosphorescence spectra of eosin in metmyoglobin due to nonequilibrium photoinduced electron transfer. The role of the matrix dynamics in photoinduced electron transfer in proteins is discussed.

Animals↗