Dual role for phenylalanine 178 during catalysis by aristolochene synthase

A mutant of aristolochene synthase, in which Phe 178 was replaced by Val, produced significant amounts of alpha- and beta-farnesene as well as alpha and beta-selinene and selina-4,11-diene, suggesting that Phe 178 is involved in the stabilisation of transition states preceding germacrene A and following eudesmane cation.