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Biomedical subjects

E I Zaichkin

Publications and source records attributed to E I Zaichkin.

18 recordsLinked to original sources
PubMed1979

[Temperature-dependent structural rearrangements in the cytoplasmic membranes of Escherichia coli cells].

By the freeze-etching method, in has been shown that E. coli plasma membranes undergo a structural transition in the range of temperatures within 0 and 20 degrees C which could be observed as redistribution of intramembrane particles with free-zone formation. The onset of temperature interval of this transition (20 degrees) well correlate with the break in the Arrhenius curves characterizing the cell membrane permeability for free nucleotides and for respiration intensity.

Cell Membrane↗
PubMed1977

The structural transitions of erythrocyte membranes induced by cyclic AMP.

The generalized structural transitions of erythrocyte membranes induced by cyclic AMP were registered by ESR, fluorescence, freeze-fracture and circular dichroism methods. Two transitions different in nature were revealed. One, which arises at 10-(11)--10-(10) M cyclic AMP, is cooperative and may be considered as a consequence of interaction of cyclic AMP with a receptor. It was calculated that a structural rearrangement in one erythrocyte ghost is induced by three cyclic AMP molecules. As a result of it the membranes are "loosened". The other transition arises at 10-(10)--10-(8) M cyclic AMP and depends on the activity of the protein kinase system. This transition was shown to be non-cooperative and due to phosphorylation of membranous proteins. During this rearrangement the membranes are "stiffened". Both transitions were demonstrated to relate to the membrane integrity.

Circular Dichroism↗
PubMed1976

[Effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in Escherichia coli cells with repressed and depressed biosynthesis of these enzymes].

Solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase. The activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes. Some data were obtained on the localization of alkaline phosphatase in a hydrophobic region, possibly in lipid bilayer and polyphosphatase in the surface layers of the membrane.

Binding Sites↗
PubMed1975

Free and bound magnesium in fungi and yeasts.

The content of total, bound and osmotically free magnesium was estimated in various fungi and in the yeast Saccharomyces cerevisiae. Total magnesium increases at lower growth rates of Endomyces magnusii and Penicillium chrysogenum 140A as well as during the logarithmic stage of growth of Penicillium chrysogenum Q-176. The binding of magnesium requires orthophosphate, decreasing during lack of external phosphate when the intracellular concentration of free magnesium rises. The fungi were found to contain a novel form of bound magnesium, a polymeric magnesium orthophosphate (PO Mg), which appears to take part in the control of free magnesium level in Penicillium chrysogenum Q-176. The level of free magnesium is proportional to the growth rate of Endomyces magnusii and Penicillium chrysogenum Q-176 and 140A. Total, as well as free, magnesium changes less than three-fold as external Mg concentration is changed 13,000-fold. The magnesium is taken up against concentration gradients of 1 : 25 to 1 : 1300, the metal being distributed non-uniformly in the cells of Saccharomyces cerevisiae.

Ascomycota↗
PubMedDate not supplied

[Effect of physicochemical factors on Bacillus thuringiensis sporulation].

Spore germination was studied in Bacillus thuringiensis subsp. galleriae. Optimal temperature regimes were selected for spore activation and initiation. The formation of spores and the rate of their subsequent germination were shown to depend on the composition of growth media in which the organism was cultivated. The paper describes changes in the fine structure of spores at different stages of their germination.

Bacillus thuringiensis↗
PubMedDate not supplied

[An electron microscopic study of the vegetative mycelia of Actinomyces flavus during flavofungin biosynthesis].

The vegetative mycelium of a submerged culture of Actinomyces flavus 12 was studied by complex electron microscopy (negative and positive contrasting, cryofractography) in the course of biosynthesis of flavofungin. The antibiotic is accumulated first in the cytoplasm as singular small granules which later grow larger. Accumulation of flavofungin is accompanied with destruction of the cytoplasm, nucleoid and other structures. Secretion of the antibiotic is supposed to be accomplished according to holocrine type.

Anti-Bacterial Agents↗