Electrophorus electricus

Enzyme Commercial acetylcholinesterase preparation - electrical organ acetone powder (extract) from electric eel (Electrophorus electricus) (Sigma, E2384) was used. 

Seto, Y. and T. Shinohara. 1987. Inhibitory effects of paraquat and its related compounds on the acetylcholinesterase activities of human erythrocytes and electric eel (Electrophorus electricus). Agric. Biol. Chem. 51 2131-2138. 

The electric eel (Electrophorus electricus) is a thin fish of length 3-5 feet see Figure 7.19. It is capable of delivering an electric shock of about 600 V as a means... 

The isolation of the nicotinic acetylcholine receptor glycoprotein was achieved almost simultaneously in several laboratories (those of Changeux, O Brien, Brady, and Eldefrawi) and was helped tremendously by the discovery that the electric organ (elec-troplax) of the electric eel (Electrophorus electricus, an inhabitant of the Amazon River) and related species, as well as the electroplax of the electric ray Torpedo tnar-morata) of the Atlantic Ocean and the Mediterranean Sea, contains acetylcholine receptors (AChR) in a much higher concentration than, for instance, in human neuromuscular endplates or brain tissue. 

M. Noda, S. Shimizu, T. Tanabe, T, Takai, T. Kayano, T. Ikeda, H. Takahashi, H. Nakayama, Y. Kanaoka, N. Minamino (1984). Primary structure of Electrophorus electricus sodium channel deduced from cDNA sequence. Nature 312 121-127. 

Making use of the binding of radioactively labeled specific toxins to identify diem, the subunits of the sodium channel proteins were purified from several sources including die electrical tissue of the electric eel Electrophorus electricus,i37 i39 heart and skeletal muscle, and brain.440-44113 In all cases a large 260-kDa glycoprotein, which may be 30% carbohydrate, is present. The saxitoxin-binding protein from rat brain has two additional 33-36 kDa subunits witii a stoichiometry of a(31P2- The Electrophorus a subunit consists of 1820 residues,437 while rat brain contains a proteins of 2009... 

The reaction of ChE s of different origin towards a homologous scries of choline esters permits a further classification within this group. This is exemplified in Fig. 1 for two representative types, the true ChE from the electric organ of Electrophorus electricus and the pseudo ChE from human plasma, both acting on acetylcholine as substrate. The curves show hydrolytic rates as function of pS = —log (substrate concentration) and demonstrate a fundamental difference between the two enzymes The true type exhibits a bell-shaped pactivity curve, indicative of autoinhibition at high substrate concentrations (18). The pseudo enzyme, on the other hand, possesses a tS-shaped curve i.e., the maximum rate is reached at and beyond an optimal substrate concentration. 

The source of enzyme was crude or partially purified membranes from the main electrical organ of Electrophorus electricus. 

Fasciculin inhibition of AChE is prevented by chemical modification of the enzyme at a peripheral site (Duran et al, 1994). The specific interaction of fasciculin 2 with peripheral sites present in Electrophorus electricus AChE Ki, 0.04 nM fasciculin) was investigated by chemical modification with A,A-dimethyl-2-phenylaziridium (DPA) in the presence of active or peripheral anionic site protective agents. An enzyme was obtained that compared to the native AChE and was 10 times less sensitive to fasciculin 2. This enzyme was fully inhibited by edrophonium and tacrine, and was 25-170 times less sensitive to several peripheral site ligands. It seems fasciculin 2 binding to an AChE peripheral site partially overlaps the site of other peripheral site ligands including acetylcholine. 

Acetylcholinesterase. Purification of acetylcholinesterase has always been problematical with complex separation procedures proving less than satisfactory. A simple one-step purification for acetylcholinesterase from the electric organ of Electrophorus electricus and bovine erythrocyte... 

Holothurin" (2x10" M) irreversibly blocks a neural and direct response of stimulated monocellular electroplax preparation of Electrophorus electricus [86]. It also produced irreversible depolarization in a monocellular electroplax preparation of Electrophorus electricus [86]. These effects on the resting potential have been attributed to an initial efflux which then decreased steadily. 

Fluorescence data for the interaction with acetylcholinesterase (EC 3.1.1.7, ACHE) from the electric eel Electrophorus electricus with some quaternary protoberberine and benzophenanthridine alkaloids was obtained. Berberine and other related compounds were bound to the gamma y-anionic site of ACHE via a comparison with known inhibitors of acetylcholinesterase, including tetramethylammonium and tacrine. Furthermore, during the interaction, two molecules of the ligand were bound to one molecule of the enzyme [226]. 

Noda M, Shimizu S, Tanabe T et al 1984 Primary structure of Electrophorus electricus sodium channel deduced from cDNA sequence. Nature 312 121-127... 

Calmodulin, by contrast, is distributed throughout most, if not all, eukaryotic cells from both animal and plant sources. It has not been reported to exist in bacteria. Calmodulin varies in concentration from tissue to tissue with mammalian brain (4) and testis (5) and the electroplax of Electrophorus electricus (6) possessing particularly high content. While the protein has been found to be predominantly cytoplasmic in subcellular fractionation studies, substantial amounts are particulate-associated as well. Binding of calmodulin to particulate fractions is increased by Ca2+, appears to occur at specific sites (7, 8), and... 

Acetylcholine Esterase Origin Electrophorus electricus Fluka... 

Leicht R, Meves H, Wellhoner H-H (1971b) Slow changes of membrane permeability in giant neurones of Helix pomatia. Pfliigers Arch 323 63-79 Levinson SR, Duch DS, Urban BW, Recio-Pinto E (1986) The sodium channel from Electrophorus electricus. Ann NY Acad Sci 479 162-178 Lipton E (1973) Effects of membrane depolarization on light scattering by cerebral cortex slices. J Physiol 231 365-383... 

Neumcke B (1990) Diversity of sodium channels in adult and cultured cells, in oocytes and in lipid bilayers. Rev Physiol Biochem Pharmacol 115 1-49 Noda M (1993) Structure and function of sodium channels. Aim NY Acad Sci 707 20-37 Noda M, Shimizu S, Tanabe T, Takai T, Kayano T, Ikeda T, Takahashi H, Nakayama H, Kanaoka Y, Minamino N, Kangawa K, Matsuo H, Raftery MA, Hirose T, Inayama LS, Hayashida H, Miyata T, Numa S (1984) Primary structure of Electrophorus electricus sodium channel deduced from cDNA sequence. Nature 312 121-127 Ohta M, Narahashi T, Keeler RF (1973) Effects of veratrum alkaloids on membrane potential and conductance of squid and crayfish giant axons. J Pharmacol Exp Ther 184 143-154... 

Rosenberg RL, Tomiko SA, Agnew WS (1984) Reconstitution ofneurotoxin-modulated ion transport by the voltage-regulated sodium channel isolated from the electroplax of Electrophorus electricus. Proc Natl Acad Sci USA 81 1239-1243... 

In 2001, using cryo-electron microscopy and single particle analysis, Sato and colleagues provided the first three-dimensional view of the Nay channel isolated from the eel Electrophorus electricus. The channel was found to have a bell-shaped extracellular surface structure with square-shaped intracellular base and a spherical top (Figure 16.10). In addition to the pore-forming a-subunits, the Nay channels have four additional accessory subunits (Naypi,-Nayp4), each measuring... 

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