Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.8 (cholinesterase)
12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a recent study (Skaaring and Bierring, 1976) we found cholinesterase-positive nerve-like structures in the lobules of rat liver, and scanning electron microscopy revealed cords having a distribution pattern similar to that of the cholinesterase-positive structures. To obtain further evidence for an intralobular nerve supply the methods of cobalt and Procion Yellow nerve staining (Stretton and Kravitz, 1968; Iles and Mulloney, 1971; Pitman, Tweedle and Cohen, 1972) were adapted, iontophoretic introduction of the dyes being attempted through cut axonal ends in the surface of small excised blocks of rat liver.
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PMID:Further evidence for the existence of intralobular nerves in the rat liver. 6 29

In rats with cobalt implanted in the right frontal cerebral cortex, acetylcholine (ACh) levels were depressed in the visually non-necotic, surrounding cortex at 7 and 14 days after surgery in comparison with values for controls treated with glass. At 21 days post-implantation, ACh levels were not different for glass and cobalt treatments. Effects of drugs affecting cholinergic function on electro-corticographic (ECoG) epileptiform activity were determined in rats implanted bilaterally with cobalt. The cholinesterase inhibitors, physostigmine and diisopropylfluorophosphate reduced both seizure activity and interictal spiking in these cobalt-treated rats. Hemicholinium-3 (HC-3), given subacutely initially inhibited seizures, but seizure frequency increased later during treatment. HC-3 did not appear to inhibit interictal spiking. These results suggest an involvement of brain cholinergic system in chronic cobalt experimental epilepsy. Seven days after cobalt implantation, HC-3 was less effective in depleting ACh in cerebral cortex adjacent to the cobalt-lesion than in similar tissue from rats with no cobalt implants. This suggests that the cholinergic neurons adjacent to the implant are not highly active at a time when seizure frequency is maximal.
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PMID:Cholinergic involvement in cobalt-induced epilepsy in the rat. 91 28

The determination of organophosphate and carbamate pesticides was carried out using cobalt phthalocyanine-modified carbon epoxy composite electrodes coupled with acetylcholinesterase or butyrylcholinesterase. Covalent immobilization of enzymes on Immobilon membranes or nylon nets was examined; the highest sensitivity to inhibitors was found for the nylon net containing low enzyme loading and this was subsequently used for the construction of an amperometric biosensor for pesticides. Analyses were done using acetyl- or butyrylthiocholine as substrates; thiocholine produced by hydrolysis in the enzyme membrane was electrochemically oxidized at +300 mV (vs. Ag/AgCl reference). The decrease of substrate steady-state current caused by the addition of pesticide was used for evaluation. With this approach, 1.5 and 8.4 micrograms l-1 of paraoxon and heptenophos, respectively, can be detected in less than 3 min. These detection limits are similar as those obtained when analyses were performed using free cholinesterase and 10 min incubation with inhibitor.
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PMID:Sensitive detection of pesticides using amperometric sensors based on cobalt phthalocyanine-modified composite electrodes and immobilized cholinesterases. 163 47

Rats were injected intraperitoneally with phenobarbital (PB) and 3-methylcholanthrene (MC) which are microsomal enzyme inducers, and methyl iodide (MeI), cobalt chloride (CoCl2) and tri-o-cresyl phosphate (TOCP) which are inhibitors of the enzymes glutathione transferase, cytochrome (cyt) P-450 and carboxylesterase, respectively, and then challenged with soman (i.p.) to know its LD50. Pretreatment with PB and MC increased and TOCP decreased, whereas MeI as well as CoCl2 did not alter the LD50 value of soman in rats. The 1/2 LD50 dose of soman did not affect the liver microsomal cyt P-450 level, but significantly lowered carboxylesterase (CaE) and cholinesterase (ChE) activities in liver microsomes and in blood plasma. Induction of plasma CaE was more important than microsomal CaE in PB-mediated protection against soman toxicity. Gel filtration of plasma into four protein fractions for their relative soman binding capacity showed that a high-molecular-weight protein fraction (180,000 daltons on SDS-PAGE) which had no CaE activity could bind soman 6 times more than the low-molecular-weight CaE-containing protein fraction (60,000 daltons on SDS-PAGE).
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PMID:Role of carboxylesterase in protection against soman toxicity. 276 74

The interaction of spin-labeled metacyn, procaine, carbolin and bivalent cations (Ca2+, Co2+, Ni2+) with butyrylcholinesterase (BChE) was studied by ESR and enzyme kinetic methods. The effect of pH, ionic strength and organic solvent was analysed. Spin-labeled metacyn binds at the anionic site of BChE active centre. This complex is stabilized both with coulombic and hydrophobic interactions, ionizing group of active centre with pK 6-7 also affects the binding. Spin-labeled procaine appeared to be enzyme competitive inhibitor (Ki = 4 X 10(-5) M) and is located, most probably, at the same site. Activating effect of Ca2+ ions on BChE was confirmed. Simultaneous application of spin labels and paramagnetic ions demonstrates that cations Co2+ and Ni2+ bind with BChE in the close vicinity of spin-labeled inhibitor site. Paramagnetic cations are located more closely to the cationic part of the inhibitor molecule than to the hydrophobic one, and can be displaced by surplus of Ca2+ ions. The experimental data testify the model of anionic centre which consists of bivalent metal ions and aminoalcyl cationic group subsites and is located in a hydrophobic pocket of the enzyme surface.
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PMID:[Binding of reversible spin-labeled inhibitors with an butyrylcholinesterase active center]. 302 29

The innervation of the diaphragm has been studied by three methods--cobalt tracing of the nerves, demonstration of cholinesterase activity and fluorescence microscopy for catecholamines and VIP. The cobalt method reveals the peripheral nerve fibers with a sharpness similar to that shown at the level of the central nervous system where this method has so far been more widely applied. The cobalt method helps to outline the distribution pattern of the nerve fibers and it can be of particular interest at the level of the viscera in order to show the different sources of the axons. Fibers giving a positive response to cholinesterase staining are shown at the level of the motor end plates and surrounding the blood vessels. It is suggested that the axons of phrenic origin contribute to the motor end plates while those coming from the vagus are distributed along the connective tissue surrounding the vascular system. Noradrenergic innervation is scarce, appearing as fine varicosities around the vascular beds. The VIPergic fibers are probably, together with the cholinergic ones, the most widespread. They are distributed among the muscle fascicules as well as being in close connection with the blood vessels.
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PMID:The autonomic innervation of the rat diaphragm. 394 43

Workers exposed to naphtha, tungsten, vanadium, cobalt and titanium exhibited decreased activity of asparagine and alanine aminotransferase, cholinesterase and ceruloplasmin in blood serum, as compared to controls. Activity of lactic acid dehydrogenase was not changed significantly. It might be surmised that absorption of metals and naphtha exhibits inhibitory properties in relation to the enzymes determined.
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PMID:[Effect of low concentrations of metals and benzin on serum enzyme activity]. 666 96

Purified human serum butyrylcholinesterase, which exhibits cholinesterase, aryl acylamidase, and peptidase activities, was cross-reacted with two different monoclonal antibodies raised against human serum butyrylcholinesterase. All three activities were immunoprecipitable at different dilutions of the two monoclonal antibodies. At the highest concentration of the antibodies used, nearly 100% of all three activities were precipitated, and could be recovered to 90-95% in the immunoprecipitate. The peptidase activity exhibited by the purified butyrylcholinesterase was further characterized using both Phe-Leu and Leu-enkephalin as substrates. The pH optimum of the peptidase was in the range of 7.5-9.5 and the divalent cations Co2+, Mn2+, and Zn2+ stimulated its activity. EDTA and other metal complexing agents inhibited its activity. Thiol agents and -SH group modifiers had no effect. The serine protease inhibitors, diisopropylfluorophosphate and phenyl methyl sulfonyl fluoride, did not inhibit. When histidine residues in the enzyme were modified by diethylpyrocarbonate, the peptidase activity was not affected, but the stimulatory effect of Co2+, Mn2+, and Zn2+ disappeared, suggesting the involvement of histidine residues in metal ion binding. These general characteristics of the peptidase activity were also exhibited by a 50 kD fragment obtained by limited alpha-chymotrypsin digestion of purified butyrylcholinesterase. Under all assay conditions, the peptidase released the two amino acids, leucine and phenylalanine, from the carboxy terminus of Leu-enkephalin as verified by paper chromatography and HPLC analysis. The results suggested that the peptidase behaved like a serine, cysteine, thiol-independent metallopeptidase.
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PMID:The peptidase activity of human serum butyrylcholinesterase: studies using monoclonal antibodies and characterization of the peptidase. 842 27

Human serum butyrylcholinesterase (BChE) has been converted into a stable but less active desensitized form when heated at 45 degrees C for 24 h. The desensitized BChE follows Michaelis-Menten kinetics, whereas native enzyme exhibits slightly negative cooperativity with respect to butyrylthiocholine binding. In this study, we investigated the effects of Ni2+, Co2+, and Mn2+ on the desensitized BChE. It is found that all three ions were noncompetitive inhibitors of the desensitized BChE, and Ki values have been determined as 7.816 +/- 1.060 mM, 48.722 +/- 4.635 mM, and 84.795 +/- 5.249 mM for Ni2+, Co2+, and Mn2+, respectively. In our previous study, these ions were linear mixed-type inhibitors of the native BChE. This finding confirms that desensitized BChE changes to a different conformation than native BChE. From the comparison of Ki values of the trace elements, it can be said that Ni2+ is a more effective inhibitor of the desensitized BChE than Co2+ and Mn2+.
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PMID:Effects of Ni(2+), Co(2+), and Mn(2+) on desensitized butyrylcholinesterase prepared from human serum. 1283 90

The effects of Ni2+, Co2+, and Mn2+ on human serum butyrylcholinesterase (BChE, acylcholine acylhydrolase E.C. 3.1.1.8) were investigated in this study. Inhibition kinetics of BChE were studied using butyrylthiocholine (BTCh) as substrate. The "1/v" versus "1/[BTCh]" plots in the absence (control plot) and in the presence of the metal ions intersected above 1/[BTCh]-axis for all trace elements. In addition, when the concentrations of the cations were increased at 4 mM BTCh, velocities decreased and drove to zero at high concentrations of the trace elements. These results demonstrate that Ni2+, Co2+, and Mn2+ are linear mixed-type inhibitors of BChE. alphaK(i) values have been determined as 53.20 mM,152.25 mM, and 190.24 mM for Ni2+, Mn2+, and Co2+, respectively, by using nonlinear regression analysis. From the comparison of alphaK(i) values of the trace elements, it can be said that BChE has more affinty to binding Ni2+ than Co2+ and Mn2+.
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PMID:The effects of Ni2+, Co2+, and Mn2+ on human serum butyrylcholinesterase. 1470 92


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