title: Steric and electronic influences on the torsional energy landscape of retinal.
abstract: We have performed quantum mechanical calculations for retinal model compounds to establish the rotational energy barriers for the C5-, C9-, and C13-methyl groups known to play an essential role in rhodopsin activation. Intraretinal steric interactions as well as electronic effects lower the rotational barriers of both the C9- and C13-methyl groups, consistent with experimental (2)H NMR data. Each retinal methyl group has a unique rotational behavior which must be treated individually. These results are highly relevant for the parameterization of molecular mechanics force fields which form the basis of molecular dynamics simulations of retinal proteins such as rhodopsin.
authors.affiliation: Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA.
authors.forename: Blake
authors.initials: B
authors.lastname: Mertz
authors.forename: Michael
authors.initials: M
authors.lastname: Lu
authors.forename: Michael F
authors.initials: MF
authors.lastname: Brown
authors.forename: Scott E
authors.initials: SE
authors.lastname: Feller
mesh_terms: D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D012172:Retinaldehyde