title: Carbocation-π interaction: evaluation of the stabilization by phenylalanine of a biochemical carbocation intermediate.
abstract: Computational analyses, using primarily density functional theory, have been used to determine the stabilization associated with the carbocation-π interaction of a biochemical carbocation intermediate binding to a phenylalanine residue in an enzyme active site. Studies of complexation between t-butyl cation and ethylbenzene, and of a model of a carbocation intermediate with a phenylalanine in the active site of geranyl diphosphate C-methyl transferase, have afforded the first quantitative evaluation of the stabilization that can be provided to a carbocation by an aromatic residue in an enzymatic reaction. Describing the hydrophobic surrounding medium using a dielectric constant between ε = 2 and ε = 4, the calculated carbocation-π stabilization energy lies in the range of 10-7.5 kcal mol-1.
authors.affiliation: Department of Chemistry, 6128 Burke Laboratory, Dartmouth College, Hanover, NH 03755, USA. robert.ditchfield@dartmouth.edu.
authors.forename: Robert
authors.initials: R
authors.lastname: Ditchfield
authors.affiliation: Department of Chemistry, 6128 Burke Laboratory, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Spencer
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry; D020134:Catalytic Domain; D008958:Models, Molecular; D010649:Phenylalanine / Q000737:chemistry*; D011789:Quantum Theory; D014166:Transferases / Q000737:chemistry / Q000378:metabolism
chemical_list: D001555:Benzene Derivatives; D010649:Phenylalanine; D014166:Transferases; C004912:ethylbenzene