Biomedical subjects

T A Zenchenko

Publications and source records attributed to T A Zenchenko.

11 recordsLinked to original sources

PubMed1996

A magnetic micromethod to measure Young's modulus of protein crystals and other polymer materials.

A new micromethod has been developed to measure the elastic modulus of polymer materials. It is based on measurements of bending of a polymer sample in a periodic uneven magnetic field acting on a small permanent magnet attached to the sample free end. As compared to the other methods known, it combines simplicity of resonant methods with a possibility to perform measurements at different frequencies in liquids under normal and high pressures. The method is specifically designed to measure the temperature dependence of cross-linked protein crystals under different conditions.

Calibration↗

PubMed1995

Mechanical deformation enhances catalytic activity of crystalline carboxypeptidase A.

A new approach for investigating mechano-chemical interactions in enzymes is described. The catalytic activity of crystalline crosslinked enzymes subjected to uniaxial deformation has been measured. Extension of monoclinic P2(1) crystals of carboxypeptidase A along the [010] direction leads to a many-fold increase in catalytic esterase activity with no changes in the effective Michaelis constant. This increase is interpreted as due to liberation of conformational mobility associated with catalytic activity of the enzyme in the deformed crystal.

Carboxypeptidases↗

PubMed1992

A new micromethod for mechano-chemical research.

A new micromethod to study activity of enzymes in crystalline and amorphous solid samples subjected to tension is described. Both static (up to 200%) and dynamic (with an amplitude up to 50% and frequency of 10(-3)-50 Hz) deformation may be applied to the sample during the activity measurement. Strain-induced changes in activity of thin (3-10 microns) needle-like strips (0.2-0.5 microns long), cut out of the microtome sections of cross-linked crystals of pancreatic carboxypeptidase A is measured in a droplet of substrate solution (with volume of 10(-6)-10(-9) l) with a pH-microelectrode technique.

Carboxypeptidases↗

PubMedDate not supplied

[Forms of histograms constructed from measurements of alpha-decay of 228Ra in Lindau (Germany) and neutron fluxes in Moscow change synchronously according to the local time].

In joint experiments performed at Max Plank Institute of Aeronomy (Germany) and the Institute of Theoretical and Experimental Biophysics in Pushchino, the main manifestations of the phenomenon of macroscopic fluctuations were confirmed. An increased probability of the similarity in synchronous histograms in independent measurements performed by two installations in one laboratory and in two laboratories separated by a distance of 2000 km was shown. In the latter case, the similarity of histograms is most probable at the same local time.

Alpha Particles↗

PubMedDate not supplied

[Correlation of fine structures of distributions of amplitudes of a photomultiplier dark current fluctuations with the Earth rotations about its axis].

The fine structures of distributions of photomultiplier dark current fluctuations measured in two laboratories 2000 km distant from other: in the international Institute of Biophysics (Neuss, Germany) and in the Moscow State University (Moscow, Russia) were compared. It is shown that similar forms of appropriate histograms are apparently more often realized at both locations at the same local time. This confirms the previous conclusion that the fine structure of distributions correlates with rotation of the Earth about its axis.

Earth, Planet↗

PubMedDate not supplied

[Regular changes in histogram forms in physical measurements and mathematical modeling].

A study of macroscopic fluctuations for objects separated by large distances confirmed the conclusion drawn earlier that, if the objects being measured are in different time zones, the increase in the probability of occurrence of histograms of similar form corresponds to the difference in the local time at the points of measurement. It was also found that, upon realization of pseudo-random sequences of numbers in mathematical generators, sequences of histograms very similar to those in real physical series can be realized. This suggests the presence of previously unknown regularities, both physical and mathematical, in sequences traditionally considered as absolutely random.

Alpha Particles↗

PubMedDate not supplied

[Quantum transitions between states and cosmophysical fluctuations].

An explanation of the appearance of the reproducible fine structure of the histograms corresponding to different processes from simple chemical reactions to radioactive decays is developed. Earlier this explanation was reduced to extremely strong influence of small changes between energy levels of a quantum system under study and its environment on the transition probability of the system (chemical reaction, radioactive decay, e.t.c.) from the system last quantum state to final result of the studied process. In the present paper it is supposed that the main factors determining this probability is the periodical or quasi-periodical low frequency changes of local gravitational field leading to corresponding changes of the system mass (the quantum transition probability depends exponentially on the latter). This approach seems to able to propose non-contradictory explanation of many manifestations of macroscopic fluctuation.

Alpha Particles↗

PubMedDate not supplied

[Dependence of 'macroscopic fluctuations" on geographic coordinates (from materials of Arctic (2000) and Antarctic (2001) expeditions].

The detailed structure of histograms constructed from the results of synchronous measurements of the alpha-activity of 239Pu microsamples, conducted in Pushchino (Moscow Region, Russia) and on board the ship "Academician Fedorov" during the Arctic and Antarctic expeditions (2000 and 2001) was analyzed. It was shown that, if the histograms were constructed over a total period of 15 min and more, the "local zone effect" and the circadian periodicity in the similarity of histogram structure, observed during measurements in Pushchino, are not found in measurements on board the ship near the North Pole (latitude 82 degrees). If the histograms were constructed over a total time of 1 min, a strict periodicity ("stellar day" 23 h 56 min) in the appearance of similar histograms in Pushchino and the Arctic and a strict synchronicity of the appearance of similar histograms of measurements in Pushchino and on board the ship at the same local geographical time were observed. During the Antarctic expedition, the effect of synchronicity of the appearance of similar histograms in Pushchino and on board the ship decreased as the ship moved towards the South Pole and the difference in latitude between the points of measurements increased.

Antarctic Regions↗

PubMedDate not supplied

[Macroscopic fluctuations: periodicity of the manifestation of "near-zone" effect].

The "near-zone effect" one of the main manifestations of the phenomenon of macroscopic fluctuations, was further investigated. It was shown that the statistical significance of the near-zone effect varies with time with a period of about 3.5 days. A phenomenological model was proposed to describe the results obtained.

Biophysical Phenomena↗

PubMedDate not supplied

[The effect of deformation on the catalytic activity of carboxypeptidase A in the crystalline state].

A new approach to study of enzyme mechano-chemistry is proposed which is based on measuring of catalytic activity of crystalline cross-linked samples subject to uniaxial tension. Deformation of monoclinic P2(1) carboxypeptidase A crystals along [010] directions results in considerable increase of their esterase activity with no changes in the Michaelis constant. This can be explained as a consequence of considerable conformational changes accompanying the enzyme cycle.

Carboxypeptidases↗

PubMedDate not supplied

[Elastic properties of triclinic crystals of lysozyme in anhydric acetonitrile].

Measurements of lysozyme crystal elastic properties in anhydrous acetonitrile were performed in order to investigate the role of water in protein elasticity. It was shown that triclinic crystals of lysozyme are suitable for such kind of investigation because of being placed in acetonitrile they save crystal lattice parameters. The observed changes of lysozyme crystals elastic properties are close to those found earlier for partially dehydrated protein. These results point to water influence on intramolecular conformational mobility of protein. The water-protein electrostatic interaction and Laplase's pressure as possible mechanisms of this influence are discussed.

Acetonitriles↗