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Biomedical subjects

E V Rozengart

Publications and source records attributed to E V Rozengart.

At least 19 recordsLinked to original sources
PubMed1999

Effects of Cd2+ and two cadmium organic complexes on isolated rat liver mitochondria.

Effects of Cd2+ and two complexes of bivalent cadmium with 1,3-bis(4-chlorbenzylidenamino)-guanidine and anabasine on ion permeability of the inner membrane and respiration of isolated rat liver mitochondria were studied. Starting from 5 microM, Cd2+ decreased state 3 and DNP-stimulated respiration of mitochondria and increased their state 4 respiration. At 30 microM, Cd2+ decreased state 4 respiration. The complexes, particularly complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine, inhibited the mitochondrial respiration at lower concentration of Cd2+. Nonenergized mitochondria incubated in media containing 125 mM of NH4NO3 or KNO3 showed more pronounced swelling in experiments with 10 microM of the complexes than with Cd2+. The complexes produced swelling of the mitochondria energized by 5 mM of succinate and incubated in medium containing 25 mM K-acetate and 100 mM sucrose. Uptake of 137-Cs by succinate-energized mitochondria in the presence of 10(-8) M of valinomycin was substantially decreased in experiments with 10 microM of the complexes than with Cd2+. Ruthenium red (7.5 microM) prevented this effect with 10 microM of complex of Cd2+ with 1,3-bis(4-chlorbenzylidenamino)-guanidine and especially complex of Cd2+ with anabasine and Cd2+. These results indicate that the cadmium organic complexes affect respiration and perturb ion permeability significantly stronger than Cd2+.

Animals↗
PubMed1996

[The action of organic cadmium complexes of different degrees of hydrophobicity on rat liver mitochondria].

Cadmium inhibits many mitochondrial enzymes participating in respiratory and oxidative phosphorylation processes, with reactive SH-groups of some of these enzymes being localized in hydrophobic domains of mitochondrial membrane. A comparative investigation was made of the action of Cd2+ and two its hydrophobic complexes (a more hydrophobic one with 1, 3-bis(4-chlorbenzilidenamino) guanidine [Cd(CBG)], and a less hydrophobic one with anabazin [Cd(ANB)] on ion permeability of the mitochondrial membrane and on respiration of rat liver mitochondria in vitro. Cd2+ ions in concentration of more than 2.5 microM and in the presence of DNP decreased mitochondrial respiration in state 3 and activated in in state 4; however, in concentration higher than 20 microM Cd2+ the activation acquired a short-term character and the state 4 respiration was seen to decrease. The experiments on mitochondrial swelling in the medium containing 125 mM NH4NO3 revealed that the complex and CBG, like Cd2+, increased proton permeability of the internal mitochondrial membrane. 10 microM Cd(ANB) and Cd(CBG) had more effect on mitochondrial respiration than Cd2+ CBG (in DNP-stimulated respiration), and ANB had no effect on mitochondrial respiration. The toxicity of Cd(CBG) was higher than that of Cd2+ and Cd(ANB), due to a higher hydrophobicity of Cd(CBG). A higher activity of Cd(CBG) was suggested to be due to its hydrophobicity. In the experiments with 137Cs in succinate-energized mitochondria at 20 degrees C and 10(-8) valinomycine, the susceptibility of toxic effects caused by the complex was lower than that caused by Cd2+ in the presence of ruthenium red, which is a blocker of Ca2+ transport. A higher Cd(CBG) effect in experiments with 137Cs and RR is accounted for by the fact that these agents are transported into mitochondria via different pathways. On the contrary, the effect of RR in similar experiments with Cd(ANB) was stronger than that of Cd2+. It is assumed that transport of Cd(ANB) in mitochondria, opposite to that of Cd(CBG), is not carried out across hydrophobic domains of the mitochondrial membrane.

Animals↗
PubMed1995

[Conformational differences in the sorption of choline ligands at the active site of acetylcholinesterase].

All the relatively stable conformers of acetylcholine, acetylthiocholine, and Rp- and Sp-enantiomers of the thiocholine-containing inhibitor of acetylcholine esterase, (CH3)2CHO(CH3)P(O)SCH2CH2N+(CH3)3, were calculated by the method of molecular mechanics. The population and the distances between functional atoms were determined for the relatively stable conformers. For the inhibitors, the accessibility of the phosphorus atom for interaction with the hydroxyl group of the Ser200 residue was determined. A computer model is proposed for the productive sorption of acetylcholine. The model assumes the contact of acetylcholine in the active center the hydroxyl group of the Ser200 residue, with the group behaving as a donor of H-bond, and also with the trimethylammonium sorptive segment. Among the organophosphorus inhibitors studied there are no relatively stable conformers that would be complementary to the sorptive site of the substrate, the choline head of the inhibitor cannot be sorbed at the trimethylammonium segment of the active center. An explanation was given for the stereospecificity of the studied enantiomers of an organophosphorus inhibitor within the limits of the proposed model.

Acetylcholinesterase↗
PubMed1992

[Dependence of anti-acetylcholinesterase effectiveness of phosphoorganic inhibitors on the accessibility of the phosphorus atom].

All equilibrium conformations of 12 anti-acetylcholinesterase organophosphorus inhibitors were calculated by the molecular mechanics method. The accessibility of the phosphorus atom of the inhibitors for interactions with the nucleophilic group at the enzyme active centre was estimated. The conformers with the phosphorus atom sterically accessible from the side opposite to the breaking ester bond were classified as productive. A correlation was revealed between the activity of the inhibitors and the population of their productive conformation.

Acetylcholinesterase↗