In many conformations, the transition state preceding the homobisabolyl cation does not lead to a minimum directly, and the homobisabolyl cation is thus located on the downward slope of an intrinisic reaction coordinate (IRC) where 1 or 2 subsequent ring-closures can occur, forming the acorenyl and cedryl cations, respectively. A 1,2-hydride shift of the (4R)-bisabolyl cation to form the (7S)-homobisabolyl cation can be accomplished in 15 different geometries with a ddG spanning 11.3 kcal/mol. Each of these conformers has been docked into the enzyme, and selected conformers were subjected to direct dynamics calculations. The inherent dynamics of these selected conformers do not match the product distribution of epi-isozizaene synthase, thus preorganization is not the only role of this enzyme. To test this possibility, a truncated active site was placed around the reacting conformer to accomplish �theozyme� dynamics calculations. Will the theozyme dynamics product distribution match the experimental product distribution?

Consequences of preorganizing homobisabolyl cation conformers for epi-isozizaene biosynthesis

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.