[A comparative study of the cholinesterase and carboxylesterase sensitivities of mammals and arthropods to new phenyl and glycidyl esters of dialkyl thiophosphoric acid].

The antienzymic activities of 14 organophosphorous compounds, the derivatives of dialkyl thiophosphoric acid, towards the acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and carboxylesterase (CE) from the spring grain aphid and mammals were investigated. The dependence of inhibitory activity of the compounds on their alkyl radical length was shown to be different for the AchE from the aphid and man. Some less pronounced differences in this dependence were revealed between the BuChEs from the aphid and horse as well as between the CEs from the aphid, mouse and red spider mite.

[Mechanism of action of thiophosphoroorganic insectoacaricides containing fragments of N-carbaalkoxylated amino acids].

Toxicity and insecticide and acaricide activity of compounds (1) is significantly dependent on the nature of amino acid (n = 1 or 2) and substituents in carbamate and amino acid ester groups (R and R1). Investigation of interaction of these compounds with mammalian carboxylesterases, and the appropriate "oxones" with choline esterases of mammal and arthropoda revealed that the lower toxicity and activity of beta-alanine derivatives (n = 2) compared with glycine derivatives (n = 1) are due to the more rapid hydrolysis by carboxylesterases (detoxication). The low toxicity of dithiophosphonate with R = Me, R1 = Bu(i), n = 1 and the high toxicity of its isomer with R = Bu(i), R1 = Me, n = 1 are associated with the more rapid oxidative cleavage of isobutyl group in comparison with the other substituents, because detoxication occurs by the cleavage of R1 and activation--by that of R respectively.

[A comparative study of the substrate and inhibitor specificity of the glutathione transferase from the spring grain aphid (Schizaphis gramina Rond.) and from rat liver].

Kinetic parameters of 9 substrates interaction with glutathione transferase (GST) from spring grain aphid and rat were studied. The most significant difference in Vmax values was noticed for 4-nitropyridine-N-oxide (6 times higher for aphid) and ethacrynic acid (7 times higher for rat). Km values were practically in all cases higher for aphid GST as compared to rat GST.

[Interaction of the rat liver glutathione transferase system with 1-phthalimidoazimines].

The interaction of rat liver glutathione and glutathione transferase with several 1-phthalimidoazimines is studied. Differences between spontaneous and enzymatic reactions of azimines and reduced glutathione are shown. It is pointed out that the formation of glutathione-azimine complexes takes place in the reaction mixture.

[Properties of cholinesterase preparations from human erythroyctes].

A modified method is described for isolation of acetylcholinesterase from human erythrocytes using an additional step of gel filtration on Sephadex G-75. Preparations of acetylcholinesterase were liberated from thromaboplastic activity and their specific activity was increased due to removal of low molecular proteins and of the products of destruction of hemoglobin. Content of A and B isoantigens in the preparations obtained was rather low and content of hemoglobin, combined with other proteins in the form of oxyhemoglobin, did not exceed 12% of the total protein.

[Ephedrine, salsoline and cytisine derivatives as substrates and inhibitirs of cholinesterases].

25 iodomethylates of acetic, propionic, butyric, isobutyric and valeric esters of N-(beta-hydroxyethyl)-derivatives of ephedrine (I) pseudo-ephedrine (II), salsoline (III), salsolidine (IV) and cytisine (V) are studied as substrates and inhibitors of acetylcholine esterase (EC 3.1.1.

[Comparative characteristics of acetylcholinesterase preparations from human erythrocytes with varying degrees of purity].

Preparations of human erythrocyte acetyl cholinesterase (HEACE) that differed in their specific activities (0.7 to 4.1 U/mg) and the final purification method were examined for protein and isoenzymic spectrum (by polyacrylamide gel disc electrophoresis), catalytic properties in the reaction of acetytriocholine hydrolysis, sensitivity to the specific organophosphorus inhibitor Gd-42, concentrations of active centres of HEACE, and activity of one catalytic centre.

[Effect of Triton X-100 on properties of acetylcholinesterase from human erythrocytes].

The effect of Triton X-100 on catalytic properties of acetylcholinesterase from human erythrocytes under acetylcholine hydrolysis, on sensitivity of acetylcholinesterase to specific phosphoorganic inhibitors and eserine, and on the mobility and isoenyme spectrum under analytical electrophoresis in polyacrylamide gel is investigated. Triton X-100, independently on its concentration within 0.05-1.

[Estimation of the irreversible inhibition reaction rate constants and of the concentration of cholinesterase active sites under commensurable concentrations of enzyme and inhibitors].

Kinetic analysis of the interaction of butyrylcholinesterase and the phosphoorganic inhibitor GT-161 [(C2H2O)2P(O)SC2H4+N(CH3)2C6H5-1-] is carried out. Short time incubations of an enzyme and an inhibitor (1-3 sec), even under commensurable concentrations, were shown to enable the rate constants of irreversible enzyme inhibition to be calcualted by the formula for pseudomonomoleuclar reactions. A simple analytical method for the estimation of the enzyme active sites concentrations is proposed.

[Determination of the rate constants for the interaction of enzymes with substrates and inhibitors during a short incubation time].

Kinetics of enzymatic reactions was studied using equipment which permitted to decrease the time of incubation of an enzyme with substrate or inhibitor up to two sec; principles of action, design and experimental procedure are described. A method of pipetting under pressure was employed to accelerate an addition of suitable reagents to the enzyme solution and for rapid stirring of the reaction mixture. Time of incubation was automatically measured with a precision of plus or minus 0.