4.2.3.9 D115E kcat/KM is 12fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 75:6:119 665301 4.2.3.9 D115N inactive mutant enzyme 665301 4.2.3.9 D116E kcat/KM is 60fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 62:3:35 665301 4.2.3.9 D116N kcat/KM is 48fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 63:2:35 665301 4.2.3.9 D203L approximately 150fold decrease in kcat/KM 729580 4.2.3.9 E119D kcat/KM is 2.4fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 94:2:4 665301 4.2.3.9 E119Q kcat/KM is 2.3fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 84:2:14 665301 4.2.3.9 E227D kcat/KM is 1182fold higher than wild-type value, in contrast to wild-type enzyme that exclusively produces aristolochene from trans,trans-farnesyl diphosphate, the mutant enzyme produces 26% aristolochene and 74% germacrene A 665301 4.2.3.9 E227Q inactive mutant enzyme 665301 4.2.3.9 E252D kcat/KM is 111fold lower than wild-type value. Wild-type enzyme produces (+)-aristolochene, (-)-valencene and (S)-(-)-germacrene A in the ratio 93:2:4, the ratio of the mutant enzyme is 19:0:81 665301