Biomedical subjects

A B Rubin

Publications and source records attributed to A B Rubin.

At least 163 records · Page 9Linked to original sources

PubMedDate not supplied

[Kinetic model of the effect of dehydration on electron transfer from membrane-bound cytochrome c to the photosynthetic reaction center].

Amplitude characteristics and kinetics of laser-induced oxidation of high-potential cytochrome CH by a photosynthetic reaction center (RC) were investigated in Ectothiorhodospira shaposhnikovii chromatophore preparations of various humidity. It is shown that the diminuition of the amount of oxidized cytochrome and the decrease of the rate of the reaction on lowering the preparation humidity can be explained in terms of the concept of conformation-controlled electron transfer within the CH-RC complex. A model is suggested which predicts that the reversible transition of the complex from one conformational state which allows electron transfer ("contact" state) to the other in which the transfer is impossible ("non-contact" state) is the result of drying (or low temperature) induced changes in the electron tunnelling path in the region of "contact" of the cytochrome CH and RC protein globules.

Bacteria↗

PubMedDate not supplied

[Polarization of photosynthetic membranes and reaction centers of Rhodopseudomonas sphaeroides 1760-1 in an external electrical field].

Electric fields as high as 10(5) V/cm cause polarization of chromatophores and reaction centre films prepared from photosynthesizing bacteria. Photosynthetic pigments, carotenoids in particular, the absorption spectra of which are changed in response to electric fields, may serve as an intrinsic indicator of the development of a polarized state. Polarization occurs due to changes in orientation and spacial position of different charge groups and particles. The field-induced polarized state can be fixed up by exposure to low temperature (-120 degrees C). While heating the system relaxes to the initial state and this can be seen as a current in an electric circuit. The effects of hydration, chemical modification or heat treatment on current indicate the involvement of macromolecule components in the formation of a polarized state, In light-adapted samples the polarization effect is markedly greater and this can indicate that conformational changes occur during the primary photoact. It is supposed that polarization might be implicated in the stabilization of separated charges and in the storage of energy.

Bacterial Chromatophores↗

PubMedDate not supplied

[Evaluation of the contribution of various types of movement of protein globules into effects observed using the Rayleigh scattering of Mössbauer radiation or the Mössbauer absorption spectroscopy].

Conditions (regions of hydration degrees and temperatures) are considered at which effects observed in Rayleigh Scattering of Mössbauer Radiation and Mössbauer Absorption Spectroscopy can be attributed to changes in intramolecular mobility, rather than contribution of different types of motions of macromolecules as a whole.

Light↗

PubMedDate not supplied

[Study of protein dynamics using Mössbauer spectroscopy].

Last experimental results of the study of protein dynamics by Mössbauer absorption spectroscopy and Rayleigh scattering of Mössbauer radiation are reviewed. Dynamical properties of proteins following from the theoretical treatment of these data are described.

Humans↗

PubMedDate not supplied

[Study of potential-dependent changes in the conformation of the beta-carotene molecule using combination scattering spectroscopy].

It has been found by Raman spectroscopy that conformational changes of beta-carotene at liposomal membrane are potential-dependent. Changes of K+ or Ca+ gradient on the liposome membrane pressed the polyene chain of beta-carotene. A mechanism of potential-dependent carotenoid conformational changes in the regulation of "antenna" or "potential sensor" in biomembrane was discussed.

Carotenoids↗

PubMedDate not supplied

[Stochastic dynamics and electron-conformation interactions in proteins].

A review of modern concepts of conformational motions in proteins is presented. Problems relevant to the theory of the dynamic behavior of different structural elements of biomacromolecules and a protein globule as a whole are discussed. A theory of electron-conformation interactions is presented and its applications to electron-transport reactions, the enzymic act, and the diffusion of the ligands in the proteins are discussed.

Animals↗

PubMedDate not supplied

[The theory of ligand migration in biomacromolecules].

A model for the process of ligand migration in bio-macromolecules is proposed. We assume that migration occurs by means of fluctuating creation of cavities in bio-macromolecules. A theory of particle migration through the fluctuating gap is created. The rate of migration is determined analytically for limiting cases. Theoretical results are applied to the migration of CO in myoglobin.

Carbon Monoxide↗

PubMedDate not supplied

[Relation of cyclic and noncyclic electron transport in Rhodospirillum rubrum chromatophores. I. Experimental study of the kinetic characteristics of dark reduction of P870 with different donor concentrations in the medium].

The kinetics of the dark recovery of photo-oxidized bacteriochlorophyll P870 was studied as a function of the intensity and duration of actinic light illumination at different concentrations of a donor in the medium. From the comparison of the experimental data with the results of mathematical modelling of the processes under investigation [1] it is concluded that electron transport is triggered for another pathway, whenever the concentration of the donor in the medium attains a certain critical level.

2,6-Dichloroindophenol↗

PubMedDate not supplied