[Mechanisms of determining target locator velocity by dolphins and technical applications in hydrolocation and radiolocation].

Dolphin's (Tursiops truncatus) capacity to discriminate between dynamic characteristics of the object location (the target moving radially) was studied. The dolphin sensitivity thresholds for target velocity (2.6 cm/s) and for target acceleration (0.6 cm/s2) were measured. It has been shown that the animal emits two-pulse probe signal to locate the target moving with constant velocity, or three-pulse probe signal--to locate the accelerated target. New highly efficient technical methods of hydro- and radiolocation were suggested on the basis of these peculiarities.

[Comparative study of enzymatic activity of cholinesterases of different origin in thionaphthylacetate hydrolysis reactions]. / Sravnitel'noe issledovanie fermentativnoi aktivnosti kholinésteraz razlichnogo proiskhozhdeniia v reaktsiiakh gidroliza tionaftilatsetata.

A comparative determination of kinetic parameters V and Km in the reaction of hydrolysis thionaphthylacetate and well known substrate acetylthiocholine by choline esterases from different sources was conducted. It is shown that butyrylcholine esterases hydrolyze thionaphthylacetate with velocity comparable with that of hydrolysis of acetylthiocholine, while acetylcholine esterases and propionylcholine esterases hydrolyze this substrate several times slower than acetylthiocholine. The values of Km in the reactions of hydrolysis of thionaphthylacetate for all studied cholinesterases is an order higher than for acetylthiocholine except cholinesterase of blood serum of fish. This value for the latter enzyme is practically equal.

[Use of 1- and 2-thionaphthylacetates as cholinesterase substrates]. / Ispol'zovanie 1- i 2-tionaftilatsetatov v kachestve substratov kholinésteraz.

1- and 2-thionaphthylacetates were tested as cholinesterase substrates. It was shown that the butyrilcholinesterase from horse serum can hydrolize these compounds. The hydrolysis velocity of 1-thionaphthylacetate was comparable with hydrolysis velocity of acetylthiocholine (the well known cholinesterase substrate), but 2-thionaphthylacetate was hydrolysed more slowly. The values of the kinetic parameters V and K(m) for butyrylcholinesterase hydrolysis of 1- and 2-thionaphthylacetates were determined. It was offered to use 1-thionaphthylacetates as the substrate for cholinesterases.

[Method for determining nitrogen-containing cationic surface-active agents using butyrylcholinesterase]. / Metod opredeleniia azotsoderzhashchikh kationnykh PAV s ispol'zovaniem butirilkholinésterazy.

The biochemical method for determination of cetyltrimethyl ammonium or cetylpyridinium, both being nitrogenated cationic surfactants, has been devised by using horse blood serum butyrylcholinesterase as analytical reagent. The method streams from the fact that surfactants tested are inhibitors of butyrylcholinesterase hydrolysis of butyrylcholin, a cationic substrate, but in this case they activate enzymatic hydrolysis of 1-naphthylacetate, a neutral substrate. Presence two opposite effects enlarges reliability to identifications. Use the sensitive fluorimetric method to registrations of activation of hydrolysis a substrate 1-naphtylacetate vastly to reduce the threshold of determination of surfactants above.

[Inhibition of cholinesterases of varying origin by ordinary and betaine vinylphosphates]. / Ugnetenie kholinésteraz razlichnogo proiskhozhdeniia obychnymi i betainovymi vinilfosfatami.

The comparative study of irreversible inhibitory action of some substituted vinyl-phosphates (in usual and betaine forms on cholinesterases from different biological sources such as the human blood erythrocytes, the horse and the hen blood serum and optic ganglia of the squid) has been carried out. It is shown that betaines obtain lesser inhibitory activity as compared with the corresponding ordinary vinylphosphates. Some of tested inhibitors display expressed selectivity of action. So, the compound GL-2 reacts with cholinesterase of optic ganglia of the squid 450 000 times faster than with cholinesterase of the hen blood serum. The application of vinylphosphates as inhibitors of cholinesterases allows displaying additional differences in properties of enzymes. It is very important for comparative enzymology. These compounds may be used for detalization of type belonging and to make the classification of cholinesterases more accurate. Moreover, the estimation of anticholinesterase activity of vinylphosphates is important because these compounds may be used both in medicine and agriculture.

[Interactions of various cationic detergents with cholinesterase of horse blood serum]. / Osobennosti vzaimodeistviia nekotorykh kationnykh detergentov s kholinésterazoi syvorotki krovi loshadi.

Cetyltrimethyl ammonium and cetylpyridinium, both being cationic detergents, have been studied for their effect on the catalytic activity of horse blood serum cholinesterase (BuHChE) in reactions of hydrolysis of carbonic acid esters. It is shown that the detergents tested are reversible competitive inhibitors of the reaction of butyryl cholinesterase hydrolysis of butyryl choline, a specific cationic substrate, but in this case they activate enzymic hydrolysis of alpha-naphthylacetate, a nonspecific neutral substrate. Values of constants, describing enzyme binding with a detergent, are estimated both by the degree of inhibition of enzymatic hydrolysis of butyryl choline and by the degree of activation of enzymatic hydrolysis of alpha-naphthylacetate and are practically equal. An assumption is made that in both cases the same complex of BuHChE with a molecule of the detergent is formed. The enzyme, as a constituent of such a complex, possesses different substrate specificity as compared with the initial one.

[Comparative characterization of the catalytic properties of blood serum cholinesterase in pigeon and hen]. / Sravnitel'naia kharakteristika kataliticheskikh svoistv kholinésterazy syvorotki krovi golubia i kur.

Significant difference in catalytic properties of partially purified cholinesterases from blood serum of pigeon and hen was shown by photometric method using Ellman's reagent. From eight studied thioesters, pigeon cholinesterase hydrolysed with the highest rate butyrylthiocholine but hen cholinesterase--propionylthiocholine. The enzymatic hydrolysis obeyed Michaelis-Menten equation only at low concentration of substrates up to 0.15-0.5 mM. High concentration of substrates activated hen cholinesterase, but inhibited pigeon cholinesterase.

[A kinetic study of the blood serum cholinesterase activity in the freshwater fish Abramis ballerus]. / Kineticheskoe issledovanie kholinésteraznoi aktivnosti syvorotki krovi presnovodnoi ryby Abramis ballerus.

In reaction of hydrolysis of choline and thiocholine esters of carbonic acids at 25 degrees C, cholinesterase activity of the blood serum from the fish A. ballerus has been studied by modified Ellman's method and potentiometric titration method. The activity is maximal in pH region 7.5-9.0 and is not inhibited by high concentration of substrates. Michaelis constants and maximal rates for the enzyme reactions were determined. Butyrylcholine and butyrylthiocholine were hydrolyzed with the highest rates by the serum. Some of the organophosphorus inhibitors (diisopropylfluorphosphate and DDVF) inhibit cholinesterase activity of the blood serum significantly faster, whereas some of the carbamates (aminostygmin, eserine, etc.) inhibit it significantly slower than typical butyrylcholinesterase from horse blood serum and typical acetylcholinesterase of human erythrocytes. Besides, with respect to the sensitivity to inhibitors and some other properties, fish blood serum cholinesterase differs from other known cholinesterases.

[Anticholinesterase activity of certain carboranyl-containing thio- and selenoesters of pentavalent phosphorus acids]. / Antikholinésteraznaia aktivnost' nekotorykh karboranilsoderzhashchikh tio- i selenoéfirov kislot piativalentnogo fosfora.

Anticholinesterase activity of carboranyl containing thio- and selenoesters of pentavalent phosphorus acids has been studied. Insertion of the carboranyl substituents in the thioester group of phosphororganic compounds was found to increase the anticholinesterase activity as compared with the thioalkyl analogues. The compounds with B-carboranyl group are less active inhibitors of cholinesterase than their isomers with C-carboranyl group.

[The mechanism of anticholinesterase action of acetylene organophosphorus inhibitors]. / O mekhanizme antikholinésteraznogo deistviia atsetilenovykh fosforororganicheskikh ingibitorov.

Introduction of the triple bond in the leaving group of the organophosphorus inhibitor molecule gives a sharp raise of the inhibitor activity but does not change principal characteristics of the cholinesterase inhibition mechanism. The reactivation experiments suggest that inactivation of cholinesterases by these compounds occurs due to phosphorylating of the serine hydroxyl by the corresponding phosphoric acid. A close similarity was shown between acetylenic and saturated organophosphorus inhibitors in altering ka upon change of pH and tetraalkylammonium ions action. It is demonstrated that S-alkynyl esters of thioacetic acid are slowly hydrolyzed by acetylcholinesterase and cholinesterase without irreversible inhibition of the enzymes.

[Reversible inhibition of cholinesterases by salts of pyrilium, thiopyrilium and selenopyrilium derivatives]. / Obratimoe ingibirovanie kholinésteraz soliami proizvodnykh piriliia, tiopiriliia i selenopiriliia.

Salts of pyrilium, thiopyrilium and selenopyrilium derivatives at pH 7.5 and temperature of 25 degrees C are studied for their effect on the catalytic activity of acetyl cholinesterase (EC 3.1.1.7) of human blood erythrocytes and butyryl cholinesterase (EC 3.1.1.8) of horse blood serum which is measured by the method of potentiometric titration. All enumerated salts are established to be strong reversible inhibitors of mixed-type cholinesterases, that is testified by small values of the inhibitory constants: competitive Ki, noncompetitive K'i and generalized K epsilon. Pyrilium and selenopyrilium salts inhibit acetyl cholinesterase of human blood erythrocytes to a higher extent than butyryl cholinesterase of horse blood serum, and thiopyrilium salts inhibit the latter to the highest extent. By the value of the inhibitory effect on acetyl cholinesterase of human blood erythrocytes thiopyrilium salts exceed the analogous pyrilium salts, whereas in experiments with butyl cholinesterase of horse blood serum there is an opposite dependence.

[A method of determining inhibitory constants during reversible inhibition of enzymatic hydrolysis of a substrate]. / Metod opredeleniia ingibitornykh konstant pri obratimom tormozhenii fermentativnogo gidroliza substrata.

Determination of inhibitory constants and antienzymic activity of reversible retardants of different type of action by the generalized inhibitory constant K sigma is estimated, results being presented. To determine more precisely the values of inhibitory constants of the competitive (Ki), noncompetitive (K'i) inhibition and of the generalized K sigma it is suggested to conduct linearization of the experimental data in coordinates: 1/K sigma, s; 1/[S], where K sigma, s is a total inhibitory constant whose value depends on the substrate [S] concentration and to make calculations by the least-square method with the allowance for principal intervals of the Km values and the maximal rate of the enzymic reaction V. Comparative calculations are made by a computer using the BASIC/RT-60 language programme through the example of the acetyl choline acetyl hydrolase (EC 3.1.1.7) interaction with the quaternary phosphonium salts--reversible retardants of this enzyme.

[Purification of acetylcholinesterase from horse erythrocytes using affinity chromatography]. / Ochistka atsetilkholinésterazy éritrotsitov krovi loshadi s pomoshch'iu affinnoi khromatografii.

A commercial preparation of water-soluble acetylcholinesterase from horse red cells has been purified to a specific activity of 2380 U/mg of protein (a 1660-fold purification) by a twofold affinity chromatography on the known sorbent of Sepharose-p-[NH-(CH2)5-C(O)NH(CH2)5C(O)NH-]-C6H4-N+(CH3)3 X Br- at pH 7.5. A selective elution of the enzyme was carried out from 10 mM of the phosphate buffer solution which contains 0.2% of triton X-100. Subsequent desorption of the enzyme proceeded with 5 mM of phenyltrimethylammonium bromide introduced into the buffer. Such effective preparations of acetylcholinesterase have not been previously produced. Effectiveness of the affinity sorbents considerably depends on the nature of the ligand which is covalent-linked with a Sepharose matrix and on the length of the attachment spacer arm ("insert") between them. A reversible inhibitory effect of certain ligands (tetramethylammonium, phenyltrimethylammonium) and their derivatives on acetylcholinesterase is estimated in comparison.

[Inhibition of cholinesterases by quaternary phosphonium compounds]. / Ingibirovanie kholinésteraz chetvertichnymi fosfonievymi soedineniiami.

Alkyl tributylphosphonium and triphenylphosphonium derivatives as well as tetraphenylphosphonium were first studied as inhibitors of acetylcholinesterase of human blood erythrocytes and butyrylcholinesterase of horse blood serum. The inhibition is reversible, of mixed type, with a different contribution of competitive and uncompetitive components. The value of the inhibitory effect is essentially dependent on the structure of phosphonium compounds, especially in experiments with butyrylcholinesterase: allyltriphenylphosphonium is 290 times as strong enzyme inhibitor as methyltributylphosphonium. Hexyltributylphosphonium is identical to hexyltributylammonium in both the pattern and efficiency of the inhibitory action on cholinesterases.

[Reversible inhibition of acetylcholinesterases of different origins by quaternary phosphonium compounds]. / Obratimoe tormozhenie atsetilkholinésteraz razlichnogo proiskhozhdeniia chetvertichnymi fosfonievymi soedineniiami.

Studies have been made on the reversible inhibition of acetylcholinesterase activity from the erythrocytes of man, horse and camel, the electric organ of the skate Torpedo marmorata and eel Electrophorus electricus, the venom of the snakes Naja naja and Vipera lebetina, the brain of the pigeon Columba livia by tetraphenyl-, triphenylalkyl- and tributyrylalkyl-phosphonium salts. The investigated phosphonium inhibitors exhibit an evident specificity in their action: they were more effective in inhibiting the acetylcholinesterase from human erythrocytes than that from the erythrocytes of horse and camel. These salts were more effective with respect to the acetylcholinesterase activity of the electric organ of the skate than that of the electric organ of the eel. Acetylcholinesterases from the venom of the snakes exhibited practically identical sensitivity to all the phosphonium compounds investigated. The present work is the first attempt to use quaternary phosphonium salts (the so-called "hydrophobic ions") in comparative enzymological investigation.