Torpedo californica

The esteratic subsite contains the catalytic machinery of the enzyme. The catalytic triad residues - Ser 200, His 440 and Glu 327 (the residue numbering in this section refers to Torpedo californica acetylcholinesterase, TcAChE) - are identical in both enzymes and basically in the same positions. 

Fig. 11.2. Schematic representation of the primary structure of secreted AChE B of N. brasiliensis in comparison with that of Torpedo californica, for which the three-dimensional structure has been resolved. The residues in the catalytic triad (Ser-His-Glu) are depicted with an asterisk, and the position of cysteine residues and the predicted intramolecular disulphide bonding pattern common to cholinesterases is indicated. An insertion of 17 amino acids relative to the Torpedo sequence, which would predict a novel loop at the molecular surface, is marked with a black box. The 14 aromatic residues lining the active-site gorge of the Torpedo enzyme are illustrated. Identical residues in the nematode enzyme are indicated in plain text, conservative substitutions are boxed, and non-conservative substitutions are circled. The amino acid sequence of AChE C is 90% identical to AChE B, and differs only in the features illustrated in that Thr-70 is substituted by Ser.

Sussman, J.L., Harel, M., Frolow, F., Oefner, C., Goldman, A., Toker, L. and Silman, I. (1991) Atomic structure of acetylcholinesterase from Torpedo californica a prototypic acetylcholine-binding protein. Science 253, 872-879. 

Elliott J, Blanchard SG, Wu W, MiUer J, Strader CD, et al. 1980. Purification of Torpedo californica post-synaptic membranes and fractionation of their constituent proteins. Biochem J 185 667. 

Schumacher, M. Camp, S. Maulet, Y. Newton, M. MacPhee-Quigley, K. Taylor, S. S. Friedmann, T. Taylor, P. Primary structure of Torpedo californica acetylcholinesterase deduced from its cDNA sequence. Nature 1986, 319, 407 09. 

The AChE inhibitory properties of the coumarins scopoletin (75) and scopolin (76) were discovered by an interesting in silico approach. A model 3-dimensional pharmacophore was constructed, using a database of known inhibitors and their interaction with the AChE from Torpedo californica. The model was then used to predict likely inhibitors from a large database of those whose molecular coordinates were known. (75) and (76) were predicted and then isolated from Scopolia carniolica and tested in the Ellman assay. Results showed that (75) was much more active than the glucoside (76) but it was 2.5 orders of magnitude weaker than galantamine. Scopoletin also showed activity in vivo when given to rats. 

Frozen electric organ from Torpedo californica (Aquatic Research Organisms, Inc., Hampton, NH) Maintain at -80°C. 

Wang, P.-R Novak, W.R.P. Cantwell, J.S. Babbitt, P.C. McLeish, M.J. Kenyon, G.L. Expression of Torpedo californica creatine kinase in Escherichia coli and purification from inclusion bodies. Protein Expr. Purif., 26, 89-95 (2002)... 

K.N. The 2.1 A structure of Torpedo californica creatine kinase complexed with the ADP-Mg -NOj-creatine transition-state analogue complex. Biochemistry, 41, 13861-13867 (2002)... 

Damle, V.N. and Karlin, A., Affinity labeling of one of two a-neurotoxin binding sites in acetylcholine receptor from Torpedo californica, Biochemistry, 17, 2039, 1978. 

Nickoloff, B.J., Grimes, M., Wohlfeil, E., and Hudson, R.A., Affinity directed reactions of 3-trimethylammoniomethyl catechol with acetylcholine receptor from Torpedo californica, Biochemistry, 24, 999, 1985. 

Nicotinic receptor from Torpedo californica Receptor was fixed into a cross-linked poly(vinylbutyral) membrane covering the gate of an ISFET which was mounted in a sample cell with a reference ISFET and Ag-AgCl reference electrode. Sensitive to ACh, H +, Na + and K +. Steady state reached after 2 min. Initial rate of change of the voltage was a rectilinear function of log ACh concentration was a from 0.1 to 10 pM. When receptor was immobilized in the membrane by using lecithin an amplified response was obtained which was due to Na + flux across receptor channel. [65]... 

Dvir, H. Wong, D. M. Harel, M. Barril, X. Orozco, M. Luque, F. J. Munoz-Torrero, D. Camps, R Rosenberry, T. L. Silman, I. Sussman, J. L. 3D stmeture of Torpedo californica acetylcholinesterase complexed with huprine X at 2.1 angstrom resolution kinetic and molecular dynamic correlates. Biochemistry, 2002, 41(9) 2970-2981. 

Doom, J.A., Thompson, C.M., Christner, R.B., Richardson, R.J. (2003). Stereoselective interaction of Torpedo californica acetylcholinesterase by isomalathion inhibitory reactions with (IR)- and (lR)-isomers proceed by different mechanisms. Chem. Res. Toxicol. 16 958-65. 

Sussman, J. L., Silman, 1. Atomic Structure of Acetylcholinesterase from Torpedo Californica A Prototypic Acetylcholine-Binding Protein, Science 1991, 253, 872-879. 

The three-dimensional structure of AChE from the electric organ of Torpedo californica has been established. One interesting feature is that the active site is embedded in a gorge of 20 A that reaches halfway into the protein. The postulated anionic site , theoretically invoked to bind the quaternary ammonium ion of ACh, appears to be represented by aromatic amino acids in the gorge itself these and charges in the active center are believed to stabilize the choline group. In addition, some inhibitions, such as that due... 

Several members of a series of hybrid molecules of THA and huperzine-A (279) were more active against acetylcholinesterase than (-)-huperzine-A,but they were not as selective for the enzyme (compared with butyryl-cholinesterase) as huperzine-A (349). Molecular modeling of compounds in the series with acetylcholinesterase from Torpedo californica showed them to interact "as truly THA-huper-zine-A hybrids." However, it was noted that acetylcholinesterase from Torpedo is somewhat different from that of humans. A subsequent paper (350) reported a study of predic-... 

Expression and Recovery of Soluble CK from Insoluble Inclusion Bodies. Construction of the Expression Vector, pKTCK3F. The cDNA insert encoding CK from the electric organ of Torpedo californica was isolated from... 

Purification of CK from the electric organ of Torpedo californica. Partially purified CK isolated from electric organ tissue was chromatographed on FPLC as described, and the major CK-containing fraction was submitted for N-terminal sequencing. This procedure showed that die first 37 amino acids were the same as those predicted by the cloned KTCK3F cDNA sequence (16), This material was used for comparison with expressed CK in subsequent experiments. It had a specific activity of 19.3 U/mg of protein. 

Figure 3. FPLC purification of refolded CK (A) CK isolated from the electric organ of Torpedo californica. (B) Expressed CK extracted with STET.

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