Calculated minimum energy conformations of acetylcholine

O.r.d. studies of β-amino ketones. I. The crystal structure and absolute configuration of (+)-(1-methyl-3-benzoyl-3-bromoacetoxypiperidine hydrobromide)

“…Quantum mechanical calculations indicate that charge is delocalized over the four carbon atoms (C +) attached to the quaternary nitrogen atom of acetylcholine (Kier, 1967;Ajo, Bossa, Damiani, Fidenzi, Gigli, Lanza & Lapiccirrella, 1972;Pullman, Courriere & Coubelis, 1971;Beveridge & Radna, 1971;Pullman & Courriere, 1972;Liquori, Damiani & DeCoen, 1968;Liquori, Damiani & Elefante, 1968). This is in accord with C~ deuteration of quaternary amines in deuterated solvents containing base (von Doering & Hoffmann, 1955;Shiner & Smith, 1958).…”

The crystal structure of a homolog of acetylcholine: 3-acetoxypropyltrimethylammonium bromide

“…There have been extensive molecular orbital calculations on the energy and electronic structure of acetylcholine over a range of different conformations (Kier, 1967;Liquori, Damiani & deCoen, 1968). More recent studies (Beveridge & Radna, 1971;Ajo, Bossa, Damiani, Fidenzi, Gigli, Lanzi & Lapiccerella, 1972;Pullman, Courriere & Coubeils, 1971) satisfactorily account for the acetylcholinc conformations which have been observed both in the crystalline state and in aqueous solution (Partington, Feeny & Burgen, 1972;Culvenor & Ham, 1970).…”

Structure of [2-(ethylideneaminooxy)ethyl]trimethylammonium iodide, C7H17N2O+.I−

“…In addition, for many muscarinic agonists the energy barriers and the energy differences between different conformers are low (Pullman & Port, 1973). The conclusions are summarized in Table 3, which lists three torsion angles of the conformation of acetylcholine-like molecules calculated by conformational analyses (Liquori, Damiani & De Coen, 1968;Kier, 1967), as concluded from the NMR study (Culvenor & Ham, 1966) and observed in acetylcholine bromide References: (a) Svinning & S6rum (1975); Liquori et al (1968); (/) Kier (1967).…”

“…The 180 ° value has been concluded from the NMR study and from the molecular-orbital-energy analysis and correlates well with the structure of L-(+)-muscarine. Liquori et al (1968) found the energy difference between the two conformations to be 1.3 kJ mol -l with the 180 ° value slightly more stable. Chothia & Pauling (1968) estimated from Liquori's results and others that the energy barrier between the two forms is about 13 kJ mol-k These two forms are those which allow a maximum interaction between an H atom on C(1) and either of the two tetrahedral electron pairs of the ether O atom.…”