Product Rearrangement from Altering a Single Residue in the Rice <i>syn</i>-Copalyl Diphosphate Synthase

Through site-directed mutagenesis targeted at identification of the catalytic base in the rice (<i>Oryza sativa</i>) <i>syn</i>-copalyl diphosphate synthase OsCPS4, changes to a single residue (H501) were found to induce rearrangement rather than immediate deprotonation of the initially formed bicycle, leading to production of the novel compound <i>syn</i>-halimadienyl diphosphate. These mutational results are combined with quantum chemical calculations to provide insight into the underlying reaction mechanism