Electrophorus

Viewing things from the perspective of his physical theory of contact electricity, Volta was intrigued by the apparently endless power of the battery to keep the electric fluid in motion without the mechanical actions needed to operate the classical, friction, electrostatic machine, and the electrophorus. He called his batteiy alternately the artificial electric organ, in homage to the torpedo fish that had supplied the idea, and the electromotive apparatus, alluding to the perpetual motion (his words) of the electric fluid achieved by the machine. To explain that motion Volta relied, rather than on the concepts of energy available around 1800, on his own notion of electric tension. He occasionally defined tension as the effort each point of an electrified body makes to get rid of its electricity but above all he confidently and consistently measured it with the electrometer. 

Skeletal muscle (muscle nAChR, comprised of al, 31,y or e, and 8 subunits, also present in electric tissues of Torpedo and Electrophorus)... 

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... 

Figure 30-17 (A) Two-dimensional map of the 260-kDa a subunit of the voltage-gated Na+ channel from the electric eel Electrophorus e/ecfns.438 441 (B) Image of the sodium channel protein obtained by cryo-electron microscopy and image analysis at 1.9 nm resolution. In this side view the protein appears to be bell-shaped with a height of 13.5 nm, a square bottom (cytoplasmic surface) 10 nm on a side, and a hemispherical top with a diameter of 6.5 nm. (C) Bottom view of the protein. (D) Axial section which cuts the bottom, as viewed in (C), approximately along a diagonal. From Sato et al.438 Notice the cavities (dark) and domain structures (light). The black arrow marks a constriction between upper (extracelllar) and lower (cytoplasmic) cavities. White lines indicate approximate position of the lipid bilayer. From Sato et al.i38 Courtesy of Chikara Sato.

Vigny, M, Bon, S, Massoulie, J, and Leterner, F (1978) Active site, catalytic efficiency of acetylcholinesterase molecular forms in electrophorus, torpedo, rat and chicken Eur J Biochem. 85, 317—323. 

Tzartos, S. J., Rand, D. E., Einarson, B. L., and Lindstrom, J. M. (1981) Mapping of surface structures of Electrophorus acetylcholine receptor using monoclonal antibodies. J Biol. Chem 256, 8635-8645. 

Noda, M. et al. (1984). Primary structure of Electrophorus sodium channel deduced from c DNA sequence. Nature (London) 312,121-127. 

True Cholinesterase from the Electric Organs of Electrophorus elec-... 

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. 

Amino acid analyses of acetylcholine esterase (AchE) and acetylcholine receptor (AchR) of Electrophorus electicus have been performed by various investig-... 

Electrophorus, 329 Electrostatic interaction, 275 Elliptic anisotropy, 289 Ellis model, 547 Elongation/Elongational, 459 at break, 454, 475 flow, 532,585 rate, 459 viscosity, 585 at yield, 457 Emeraldine, 344 End-to-end distances, 246, 248 End groups, 7, 8 End of pyrolysis, 765... 

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. 

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