A hypothesis for the mechanism of sodium channel opening by batrachotoxin and related toxins

AbstractThe mechanism of action of one class of sodium channel opening agents (batrachotoxinin, veratridine, aconitine and grayanotoxin) is proposed to involve complexation of a triad of agent oxygen atoms with the ε-ammonium ion of a channel lysing side chain, holding open the mouth or exit of the ion channel. This idea complements the oxygen triad model derived by structural considerations (Masutani, T., Seyama, I., Narahashi, T. and Iwasa, J. (1981) J. Pharm. Exp. Therap. 217,812) and extended by crystal structure comparisons (Codding, P.W. (1983) J. Am. Chem. Soc. 105, 3172). The mechanism is based on results for acetylcholine receptor ion channel gating, structure and function, using single group rotation (SGR) theory (cf. Kosower, E.M. (1983) Biochem. Biophys. Res. Commun. 111, 1022 and in press (1983);FEBS Lett. (1983) 155, 245; ibid. 157, 144; Biophys. J. (1983) 45, in press)

Optical spectra and reactivities of radical anions of 4-nitrobenzyl compounds produced by pulse radiolysis of acetonitrile solutions

Electronic absorption spectra are reported for transients formed on pulse radiolysis of acetonitrile solutions of aromatic nitrobenzyl compounds and are assigned to the solute radical anions. Decay of the transients is fairly rapid but is markedly slower in the presence of tetraethylammonium formate. It is suggested that the CH2CN radical is responsible for the rapid decay and that formate ion scavenges this species. With 4-nitrobenzyl chloride, the decay of the transient is observed to be second order, in contrast to electrochemical experiments where first-order decay is observed. With 4-nitrobenzyl fluoride or alcohol, decay of the initially formed transient is accompanied by formation of a new species absorbing at longer wavelength. Identification of the 4-nitrobenzyl chloride anion is supported by first-order decay of the species in water with k = 4 x 103 sec-1 (found by Hayon and Madhavan)

A molecular model for the bilayer helices of the acetylcholine receptor including an acetylcholine binding site

AbstractA molecular model for the bilayer helices of the acetylcholine receptor is constructed from the 7 channel elements and the 17 hydrophobic helices of the 5 protein subunits. The acetylcholine binding site and the opening to the ion channel are included

Spectroscopie ultraviolette et mesure empirique de la polarité du solvant (constante Z)

La bande de transfert de charge des iodures d’alcoyl-1 pyridinium est extrêmement sensible au solvant. Les énergies de transitions pour la transition CT de l’iodure d’éthyl-1 carbométhoxy-4 pyridinium, exprimées en kcal/mole, ont été appelées constantes Z, mesure empirique de la polarité des solvants. Quelques applications sont discutées

An introduction to physical, organic chemsitry

xvii, 503 p.; 21 cm