scholarly journals Diadenosine polyphosphate hydrolase from presynaptic plasma membranes of Torpedo electric organ

1997 ◽  
Vol 323 (3) ◽  
pp. 677-684 ◽  
Author(s):  
Jesús MATEO ◽  
Pedro ROTLLAN ◽  
Eulalia MARTI ◽  
Inmaculada GOMEZ DE ARANDA ◽  
Carles SOLSONA ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Pyridoxal Phosphate ◽  
Electric Organ ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Ic50 Value ◽  
Neural Origin ◽  
Disulphonic Acid ◽  
Torpedo Electric Organ ◽  
Enzyme Activators

The diadenosine polyphosphate hydrolase present in presynaptic plasma membranes from the Torpedo electric organ has been characterized using fluorogenic substrates of the form di-(1,N6-ethenoadenosine) 5´,5‴-P1,Pn-polyphosphate. The enzyme hydrolyses diadenosine polyphosphates (Apn A, where n = 3–5), producing AMP and the corresponding adenosine (n-1) 5´-phosphate, Ap(n-1). The Km values of the enzyme were 0.543± 0.015, 0.478±0.043 and 0.520±0.026 μM, and the Vmax values were 633±4, 592±18 and 576±45 pmol/min per mg of protein, for the etheno derivatives of Ap3A (adenosine 5´,5‴-P1,P3-triphosphate), Ap4A (adenosine 5´,5‴-P1,P4 -tetraphosphate) and Ap5A (adenosine 5´,5‴-P1,P5-pentaphosphate) respectively. Ca2+, Mg2+ and Mn2+ are enzyme activators, with EC50 values of 0.86±0.11, 1.35±0.24 and 0.58±0.10 mM respectively. The fluoride ion is an inhibitor with an IC50 value of 1.38±0.19 mM. The ATP analogues adenosine 5´-tetraphosphate and adenosine 5´-[γ-thio]triphosphate are potent competitive inhibitors and adenosine 5´-[α,β-methylene]diphosphate is a less potent competitive inhibitor, the Ki values being 0.29±0.03, 0.43±0.05 and 7.18±0.8 μM respectively. The P2-receptor antagonist pyridoxal phosphate 6-azophenyl-2´,4´-disulphonic acid behaves as a non-competitive inhibitor with a Ki value of 29.7±3.1 μM, and also exhibits a significant inhibitory effect on Torpedo apyrase activity. The effect of pH on the Km and Vmax values, together with inhibition by diethyl pyrocarbonate, strongly suggests the presence of functional histidine residues in Torpedo diadenosine polyphosphate hydrolase. The enzyme from Torpedo shows similarities with that of neural origin from neurochromaffin cells, and significant differences compared with that from endothelial vascular cells.

scholarly journals Large-scale purification of presynaptic plasma membranes from Torpedo marmorata electric organ.

1985 ◽  
Vol 101 (5) ◽  
pp. 1757-1762 ◽  
Author(s):  
N Morel ◽  
J Marsal ◽  
R Manaranche ◽  
S Lazereg ◽  
J C Mazie ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Large Scale ◽  
Plasma Membranes ◽  
Electric Organ ◽  
Acetylcholinesterase Activity ◽  
Cholinergic Nerve Terminals ◽  
Membrane Bound ◽  
Torpedo Electric Organ ◽  
Presynaptic Plasma Membrane ◽  
Glycera Convoluta

The presynaptic plasma membrane (PSPM) of cholinergic nerve terminals was purified from Torpedo electric organ using a large-scale procedure. Up to 500 g of frozen electric organ were fractioned in a single run, leading to the isolation of greater than 100 mg of PSPM proteins. The purity of the fraction is similar to that of the synaptosomal plasma membrane obtained after subfractionation of Torpedo synaptosomes as judged by its membrane-bound acetylcholinesterase activity, the number of Glycera convoluta neurotoxin binding sites, and the binding of two monoclonal antibodies directed against PSPM. The specificity of these antibodies for the PSPM is demonstrated by immunofluorescence microscopy.

Characterization of a rabbit serum raised against a botulinum toxin type a binding protein from presynaptic plasma membranes from Torpedo electric organ

Toxicon ◽  
1995 ◽  
Vol 33 (4) ◽  
pp. 507-514 ◽  
Author(s):  
Josep M. Canals ◽  
Monica Arribas ◽  
Luis Ruiz-Avila ◽  
Joan M.V. Blasi ◽  
Jordi Marsal ◽  
...  
Keyword(s):  
Botulinum Toxin ◽  
Plasma Membranes ◽  
Binding Protein ◽  
Botulinum Toxin Type A ◽  
Electric Organ ◽  
Type A ◽  
Botulinum Toxin Type ◽  
Rabbit Serum ◽  
Torpedo Electric Organ

scholarly journals Binding of a Glycera convoluta neurotoxin to cholinergic nerve terminal plasma membranes.

1983 ◽  
Vol 97 (6) ◽  
pp. 1737-1744 ◽  
Author(s):  
N Morel ◽  
M Thieffry ◽  
R Manaranche
Keyword(s):  
Nerve Terminal ◽  
Concanavalin A ◽  
Plasma Membranes ◽  
Acetylcholine Release ◽  
Motor Nerve ◽  
Biological Response ◽  
Electric Organ ◽  
Venom Glands ◽  
Torpedo Electric Organ ◽  
Glycera Convoluta

The crude extract of venom glands of the polychaete annelid Glycera convoluta triggers a large Ca2+-dependent acetylcholine release from both frog motor nerve terminals and Torpedo electric organ synaptosomes. This extract was partially purified by Concanavalin A affinity chromatography. The biological activity was correlated in both preparations to a 300,000-dalton band, as shown by gel electrophoresis. This confirmed previous determinations obtained with chromatographic methods. This glycoprotein binds to presynaptic but not postsynaptic plasma membranes isolated from Torpedo electric organ. Pretreatment of intact synaptosomes by pronase abolished both the binding and the venom-induced acetylcholine release without impairing the high K+-induced acetylcholine release. Pretreatment of nerve terminal membranes by Concanavalin A similarly prevented the binding and the biological response. Binding to Torpedo membranes was still observed in the presence of EGTA. An antiserum directed to venom glycoproteins inhibited the neurotoxin so we could directly follow its binding to the presynaptic membrane. Glycera convoluta neurotoxin has to bind to a ectocellularly oriented protein of the presynaptic terminal to induce transmitter release.

scholarly journals Inhibitory Effect of Fisetin on α-Glucosidase Activity: Kinetic and Molecular Docking Studies

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5306
Author(s):  
Beiyun Shen ◽  
Xinchen Shangguan ◽  
Zhongping Yin ◽  
Shaofu Wu ◽  
Qingfeng Zhang ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Inhibitory Activity ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Docking Studies ◽  
Molecular Docking Studies ◽  
Ic50 Value ◽  
Cotinus Coggygria

The inhibition of α-glucosidase is a clinical strategy for the treatment of type 2 diabetes mellitus (T2DM), and many natural plant ingredients have been reported to be effective in alleviating hyperglycemia by inhibiting α-glucosidase. In this study, the α-glucosidase inhibitory activity of fisetin extracted from Cotinus coggygria Scop. was evaluated in vitro. The results showed that fisetin exhibited strong inhibitory activity with an IC50 value of 4.099 × 10−4 mM. Enzyme kinetic analysis revealed that fisetin is a non-competitive inhibitor of α-glucosidase, with an inhibition constant value of 0.01065 ± 0.003255 mM. Moreover, fluorescence spectrometric measurements indicated the presence of only one binding site between fisetin and α-glucosidase, with a binding constant (lgKa) of 5.896 L·mol−1. Further molecular docking studies were performed to evaluate the interaction of fisetin with several residues close to the inactive site of α-glucosidase. These studies showed that the structure of the complex was maintained by Pi-Sigma and Pi-Pi stacked interactions. These findings illustrate that fisetin extracted from Cotinus coggygria Scop. is a promising therapeutic agent for the treatment of T2DM.

Synthesis and Assessment of Novel Anti-chlamydial Benzylidene Acylhydrazides Derivatives

2018 ◽  
Vol 15 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Xiaofeng Bao ◽  
Ying Xue ◽  
Chao Xia ◽  
Yin Lu ◽  
Ningjing Yang ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Dependent Manner ◽  
Iron Starvation ◽  
Hydrochloride Salt ◽  
Obligate Intracellular ◽  
Biphasic Life Cycle ◽  
Ic50 Value ◽  
Ic50 Values ◽  
Dose Dependent ◽  
Better Than

Background: Chlamydiae, characterized by a unique biphasic life cycle, are a group of Gram-negative obligate intracellular bacterial pathogens responsible for diseases in a range of hosts including humans. Benzylidene acylhydrazide CF0001 could inhibit chlamydiae independent of iron starvation and T3SS inhibition. This finding promoted us to design and synthesize more benzylidene acylhydrazides to find novel anti-chlamydial agents. Methods: The carboxylic acids 1a-1d were coupled with Boc-hydrazide inpresence of EDCI and DMAP to obtain the intermediate 2a-2d in 60-62% yields. N-Boc deprotections were performed to obtain hydrazide hydrochloride salt 3a-3d. Nextly, the hydrazides were subjected to condensation with aldehydes to obtain benzylidene acylhydrazides 4a-4g in 30-52% yields in two steps. Results: Compound 4d exhibited best inhibitory effect on the formation and growth of chlamydial inclusions. The IC50 value of compound 4d for infectious progenies was 3.55 µM, better than 7.30 µM of CF0001. Conclusion: To find novel anti-chlamydial agents, we have designed and synthesized benzylidene acylhydrazides 4a-4g. Compounds 4a, 4d, 4g showed inhibitory activity on C. muridarum with the IC50 values from 3.55-12 µM. The 3,5-dibromo-4-hydroxyl substitutes on ring B are critical to keep their anti-chlamydial activity. Compound 4d inhibited C. muridarum in a dose-dependent manner without apparent cytotoxicity.

scholarly journals Development of Halogenated Pyrazolines as Selective Monoamine Oxidase-B Inhibitors: Deciphering via Molecular Dynamics Approach

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3264
Author(s):  
Aathira Sujathan Nair ◽  
Jong-Min Oh ◽  
Vishal Payyalot Koyiparambath ◽  
Sunil Kumar ◽  
Sachithra Thazhathuveedu Sudevan ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Monoamine Oxidase ◽  
Phenyl Ring ◽  
Competitive Inhibitor ◽  
Selectivity Index ◽  
Monoamine Oxidase A ◽  
Mao B ◽  
Ic50 Value ◽  
The Central Nervous System ◽  
Inhibitory Activities

Halogens have been reported to play a major role in the inhibition of monoamine oxidase (MAO), relating to diverse cognitive functions of the central nervous system. Pyrazoline/halogenated pyrazolines were investigated for their inhibitory activities against human monoamine oxidase-A and -B. Halogen substitutions on the phenyl ring located at the fifth position of pyrazoline showed potent MAO-B inhibition. Compound 3-(4-ethoxyphenyl)-5-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole (EH7) showed the highest potency against MAO-B with an IC50 value of 0.063 µM. The potencies against MAO-B were increased in the order of –F (in EH7) > –Cl (EH6) > –Br (EH8) > –H (EH1). The residual activities of most compounds for MAO-A were > 50% at 10 µM, except for EH7 and EH8 (IC50 = 8.38 and 4.31 µM, respectively). EH7 showed the highest selectivity index (SI) value of 133.0 for MAO-B, followed by EH6 at > 55.8. EH7 was a reversible and competitive inhibitor of MAO-B in kinetic and reversibility experiments with a Ki value of 0.034 ± 0.0067 µM. The molecular dynamics study documented that EH7 had a good binding affinity and motional movement within the active site with high stability. It was observed by MM-PBSA that the chirality had little effect on the overall binding of EH7 to MAO-B. Thus, EH7 can be employed for the development of lead molecules for the treatment of various neurodegenerative disorders.

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