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Biomedical subjects

L A Bliumenfel'd

Publications and source records attributed to L A Bliumenfel'd.

At least 19 recordsLinked to original sources
PubMed1976

[Relation of growth and decay kinetics of the microwave photoconductivity signal of Chlorella to its culture state].

Signals of microwave photoconductivity (MPC) of Chlorella cells in various physiological states and at various illumination conditions have been studied. It was shown that cells of high photosynthetic activity and unruptured electron transfer system give MPC signals of the type I (nonmonotonic rise and decay kinetics). A decrease of photosynthetic activity leads to the appearance of MPC signals of the type II (monotonic rise and decay kinetics).

Chlorella↗
PubMedDate not supplied

[Dynamic theory of enzymatic catalysis].

Formal kinetics of an enzymatic reaction is considered in terms of a dynamic scheme of catalysis. Conformation reconstructions of a liberated enzyme and e-s-complex are analysed upon the phase plane. An expression for the enzyme stationary activity depending on the rate of conformation reconstructions is obtained. The case of purely dynamic catalysis is analysed and possible initiation of enzymatic activity variation in time connected with initial synchronization of molecules is shown. This phenomenon is considered as a possible criterion of the dynamic character of enzymatic catalysis.

Catalysis↗
PubMedDate not supplied

[Several physical aspects of intracellular energy transformation].

Physical principles underlying the chemiosmotic hypothesis of membrane phosphorylation are analysed. The utilization of free energy determined by dydrogen ions concentration difference across the membrane for ATP synthesis requires ATP-synthetase to be an entropy machine able to perform work on account of heat. The chemiosmotic hypothesis assumes the possibility of interchangeable utilization of both components of proton electrochemical potential-the membrane electrical difference and proton concentration gradient-for ATP synthesis. This assumption requires the fulfillment of practically unrealizable conditions. Energetic coupling of intracellular chemical reactions must be realized by means of a mechanism in which every act of energydonating reaction leads compulsory to one act of energyaccepting reaction. For such a mechanism both reactions ought to proceed essentially in one elementary act. For intracellular macromolecular and supramolecular systems it implies the necessity of excitation of specific mechanical slowly relaxing degrees of freedom.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Temperature dependence of the epr spectra of a spin-labeled myosin and its complex with adp].

The effect of temperature on ESR spectra of spin-labelled myosin and myosin-ADP complex was studied. It was shown that mobility of the sptrongly immobilized spin label almost did not change with temperature (-2 degrees C-37 degrees C) whereas mobility of the slightly immobilized spin label changed in a complicated manner and not monotonously. The observed changes in mobility of the slightly immobilized spin label and characteristics of the ESP spectrum of the myosin-ADP complex suggest that temperature causes continuous changes of the structure in the local environment of the binding sites of the spin label, and on the average, one conformation of myosin and myosin-ADP complex molecules exists at any temperature.

Adenosine Diphosphate↗
PubMedDate not supplied

[Formation of a complex between carbon monoxide and cytochrome C].

The conditions of structural modifications of horse heart cytochrome c (pH, salt concentration) have been studied. Under these conditions the rate of carboxycytochrome c formation greatly increases in the course of the reduction process as compared to this rate after cytochrome c reduction and relaxation to the equilibrium state. According to these results the reduced intermediate which appears in the course of reduction has a high affinity for the carbon monoxide. It has been shown that the reduced low-spin cytochrome c practically does not take part in the process of dynamic conformational equilibrium with other cytochrome c forms existing in equilibrium mixture of oxidized and reduced cytochrome c.

Carbon Monoxide↗
PubMedDate not supplied

[Study of conformational transitions in myosin using 2 types of spin label].

It is shown that three types of ESR spectra of myosin labeled with both acetate and acetamide spin labels are distinguished. These three types are the spectrum of initial preparation, myosin--ADP complex spectrum and the spectrum recorded during ATP hydrolysis. The ESR spectra of myosin labeled with acetate spin label are more sensitive to conformational changes of myosin induced by complex formation and temperature.

Cyclic N-Oxides↗
PubMedDate not supplied

[Chemical characteristics of conformationally-disequilibrium states of metal-containing proteins].

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

[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↗