Human cholinesterase has recently been sequenced and cloned. It is a glycoprotein of 4 identical subunits, each subunit containing 9 carbohydrate chains and 3.5 disuljide bonds. Protein folding is likely to be very similar in human cholinesterase and Torpedo acetylcholinesterase. The cholinesterases have no significant sequence homology with the serine proteases and seem to belong to a separate...

Background: The lipid sensitivity of the prokaryotic pentameric ligand-gated ion channel (pLGIC), GLIC, is poorly characterized. Results: GLIC is more thermally stable and does not exhibit the same propensity to adopt an uncoupled conformation as the Torpedo nAChR. Conclusions: GLIC is less sensitive to its surrounding membrane environment. Significance: The GLIC and nAChR structures suggest mo...

To study pathways by which acetylcholine receptor (AChR) subunits might assemble, Torpedo alpha subunits were expressed in Xenopus oocytes alone or in combination with beta, gamma, or delta subunits. The maturation of the conformation of the main immunogenic region (MIR) on alpha subunits was measured by binding of mAbs and the maturation of the conformation of the AChR binding site on alpha su...

Huprine X is a novel acetylcholinesterase (AChE) inhibitor, with one of the highest affinities reported for a reversible inhibitor. It is a synthetic hybrid that contains the 4-aminoquinoline substructure of one anti-Alzheimer drug, tacrine, and a carbobicyclic moiety resembling that of another AChE inhibitor, (-)-huperzine A. Cocrystallization of huprine X with Torpedo californica AChE yielded...

The lipid requirements of the Torpedo californica nicotinic acetylcholine receptor (nAChR) were assessed by reconstituting purified receptors into lipid vesicles of defined composition and by using photolabeling with 3-trifluoromethyl-3-(m-[125I]iodophenyl)diazirine ([125I]TID) to determine functionality. Earlier studies demonstrated that nAChRs reconstituted into membranes containing phosphati...

Torpedo acetylcholinesterase is irreversibly inactivated by modifying a buried free cysteine, Cys231, with sulfhydryl reagents. The stability of the enzyme, as monitored by measuring the rate of inactivation, was reduced by mutating a leucine, Leu282, to a smaller amino acid residue. Leu282 is located within the "peripheral" anionic site, at the entrance to the active-site gorge. Thus, loss of ...

The effects of receptor activation were studied on the interaction of perhydrohistrionicotoxin (H(12)-HTX) with the ionic channel of the nicotinic acetylcholine (AcCho) receptor in membranes from the electric organ of Torpedo ocellata and with the endplate region of the soleus muscle of the rat. In Torpedo membranes, the initial rate (i.e., within 30 sec) of [(3)H]H(12)-HTX bindings to the ioni...

A basic theory of two-dimensional cyclic codes (TDC codes) is presented. This theory is applicable to the binary TDC codes of odd area, i.e., the TDC codes with an odd number of symbols from GF(2). It is shown that such TDC codes are completely characterized by the common zeros, which correspond to the roots for ordinary cyclic codes. The fundamental structure of the codes such as the positions...