Title: [Comparative study of enzymatic activity of cholinesterases of different origin in thionaphthylacetate hydrolysis reactions] Zhukovskii Iu G, Kuznetsova LP, Sochilina EE, Veksler KV Ref: Ukr Biokhim Zh (1999), 76:151, 2004 : PubMed
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.
Title: [The inhibition enzymatic hydrolysis of acetylthiocholine by acetylcholinesterase using principal alkaloids isolated from celandine and macleya and their derivatives] Kuznetsova LP, Nikol'skaia EB, Sochilina EE, Faddeeva MD Ref: Tsitologiia, 43:1046, 2001 : PubMed
A study was made of a possible inhibitory action on the enzymatic hydrolysis of acetylthiocholine by human erythrocyte acetylcholinesterase of principal alkaloids isolated from Chelidonium majus L. and Macleaya (Bocconia) cordata and microcarpa (namely sanguinarine, chelidonine, berberine), and of drugs "Ukrain" (thiophosphoric acid derivative of a sum of the alkaloids isolated from Chelidonium majus L.) and "Sanguirythrine" (a mixture of unseparated closely related to benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine, isolated from Chelidonium majus L. and other plants of Papaveraceae family). All agents under study have been shown to be reversible inhibitors of the enzymatic hydrolysis of acetylthiocholine. On the basis of the kinetic data it has been determined that chelidonine belonged to reversible inhibitors of a competitive type. All other examined agents have been demonstrated to be inhibitors of a mixed competitive-noncompetitive type, and a greater contribution to the inhibition was made by the competitive constituent. Among all examined agents berberine, sanguinarine and "Sanguirythrine" were the strongest inhibitors of this reaction (the values of generalized inhibitory constants being 0.23, 0.23 and 0.29 microM, respectively) and cheliodonine and "Ukrain" were much weaker (2.0 and 2.5 microM, respectively). Judging from the data obtained, sanguinarine and chelerythrine exert similar inhibitory effects on the reaction of enzymatic hydrolysis of acetylthiocholine, since sanguinarine and "Sanguirythrine" have nearly equal generalized inhibitory constants.
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.
The action of some phosphonium betains on cholinesterases from different biological sources has been studied. It has been shown, that all studied betains are reversible inhibitors of cholinesterase hydrolysis of acetyltiocholine. Inhibiting action of these compounds on acetylcholinesterases is about ten times weaker that of the majority of known phosphonium salts, while their action on butyrylcholinesterases has no peculiarities. There were found certain differences for each betain compounds in their action on cholinesterases from different biological sources. These results may be used for detail classification of cholinesterases and allow to extend knowledge in comparative enzymology.
Title: [Catalytic properties of cholinesterases immobilized in N-phthalylchitosan and gelatin] Kuznetsova LP, Nikol'skaia EB Ref: Ukr Biokhim Zh (1978), 67:49, 1995 : PubMed
Catalytic properties of human blood erythrocyte acetylcholinesterase, horse blood serum butyrylcholinesterase and squid visual cholinesterase nonimmobilized and immobilized in N-phthalylchitozane and in gelatin have been comparatively studied. Immobilization of cholinesterases in N-phthalylchitozane does not change its catalytic properties in respect to substrates and inhibitors but increases the enzyme stability. Cholinesterase immobilization in the gelatin membrane increases the Michaelis constants and decreases the maximum velocities in the reaction of enzyme hydrolysis of thiocholine esters and (for squid visual ganglia cholinesterase) of indophenylacetate. The effect of irreversible inhibitor diisopropylfluorophosphate and reversible inhibitors N-methyl-4-piperidinyl benzylate and tacrine on cholinesterases immobilized in the gelatin is weaker as compared with the effect on nonimmobilized enzymes. The results obtained are discussed for the effect of immobilization on the active enzyme surface.
Title: [Interactions of various cationic detergents with cholinesterase of horse blood serum]. [Russian] Zhukovskii Iu G, Kuznetsova LP, Sochilina EE Ref: Ukrainskii Biokhimicheskii Zhurnal, 67:40, 1995 : PubMed
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.
Title: [Features of inhibition of butyrylcholinesterase and carboxylesterase hydrolysis of fluoroanhydride esters by beta,beta- diphenylethylphosphonic acid] Brestkin AP, Nikol'skaia EB, Kuznetsova LP, Efimtseva EA, Fridland SV Ref: Doklady Akademii Nauk, 339:816, 1994 : PubMed
The kinetic analysis of cholinesterase interaction with reversible inhibitors was carried out. It has shown that the existing methods for definition of the type of reversible inhibition of enzyme reactions are not reliable. For example, mixed inhibition with the correlation between the competitive inhibition constant (Kl) and noncompetitive inhibition constant (K'i) less than 0.04, is identified as competitive inhibition. Apparently the ideal competitive inhibition with Ki/Ki = 0 does not exist in reality, because it is unlikely for a reversible inhibitor to decrease the process of the substrate sorption on a catalytical centre of cholinesterase not affecting the deacetylation rate. For objective evaluation of efficiency of reversible inhibitors it is suggested to determine the generalized inhibitory constant Ki at the cholinesterase hydrolysis in acetylcholine or acetylthiocholine. The data about anticholinesterase activity of carbonic and sulfoesters of lupinin are adduced.
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.
Title: [Influence of the substrate nature, ethanol and phosphate buffer on the butyrylcholinesterase hydrolysis retardation by reversible inhibitors] Brestkin AP, Kuznetsova LP, Nikol'skaia EB Ref: Ukr Biokhim Zh, 63:51, 1991 : PubMed
The reversible inhibition of horse blood serum butyrylcholinesterase (Ce 3.1.1.8) hydrolysis of ion substrates of acetyl- and butyrylthiocholines and non-ion substrate of indophenylacetate by N-methyl-4-piperidinylbenzylate and tacrine (1,2,3,4,-tetrahydro-9-aminoacridine) and phosphate buffer and ethanol influence on this process are investigated. The values of competitive Ki, uncompetitive K'i and generalized K sigma inhibitory constants are determined. It is shown that the inhibition effect and reversible inhibition type depend not only on the inhibitor and substrate nature but also on the phosphate buffer concentration and ethanol presence in the reaction mixture.
Catalytic properties of human blood erythrocyte acetylcholinesterase and horse blood serum butyrylcholinesterase immobilized and nonimmobilized in the gelatin membrane have been comparatively studied. Cholinesterase immobilization induces an increase in the Michaelis constant value and a decrease in the maximum rate value in reactions of enzymic hydrolysis of thiocholine ethers, but exerts no effect on these kinetic parameters in case of enzymic hydrolysis of indophenylacetate. The effect of reversible inhibitors: galanthamine, N-methyl-4-piperidinyl benzylate and 1,2,3,4-tetrahydro-9-aminoacridine (tacrine), as well as of irreversible inhibitors: O-ethyl-O-(4-nitrophenyl)ethyl phosphonate (armin), diisopropyl fluorophosphate (DFP), O,O-diethyl-O-(4-nitrophenyl) phosphate (paraoxon) and O,O-dimethyl-O-(2,2-dichlorovinyl) phosphate (DDVP) on immobilized cholinesterases is weaker as compared with the effect on nonimmobilized enzymes. The results obtained are discussed for the effect of immobilization on the catalytically active enzyme surface.
Title: [Effect of salt composition of the medium and ethanol on cholinesterase hydrolysis of various substrates] Kuznetsova LP, Nikol'skaia EB Ref: Ukr Biokhim Zh, 60:35, 1988 : PubMed
Sodium chloride, phosphate buffer and ethanol were studied for their effect on butyryl cholinesterase hydrolysis rate of acetylcholine, acetylthiocholine, butyrylthiocholine and nonion substrate of indophenylacetate. The concentrations of 1.10(-2) = 1.10(-1) M of sodium chloride activated enzymatic hydrolysis of ion substrates at the concentrations lower than 1.10(-4) M but sodium chloride is a competitive inhibitor at higher concentrations. Phosphate buffer also activates substrates enzyme hydrolysis at the concentrations of 2.10(-4) M and lower, but it inhibits incompetitively the nonion substrate indophenylacetate hydrolysis. Ethanol activates butyrylthiocholine hydrolysis and is a competitive inhibitor in acetylthiocholine and indophenylacetate hydrolysis. The observed effects are discussed on the assumption of two forms of butyrylcholinesterase E' and E" existence. These two forms are determined by different kinetic parameters and are in equilibrium.
