Calculated activation barriers of Spinosyn A formation.

Calculated ΔE≠2-TS activation barriers (in kcal/mol) of the cycloaddition step involved in the biosynthesis of Spinosyn A showing effect of amino acids coordination. See S5 Fig; S6 Fig; S7 Fig; S8 Fig and S5 Table for structures and geometric parameters.[a] Coordinated amino acids: 1—none; 2—Gln; 3—Gln and Ser; 4—Gln and 2 molecules of Ser.[b] Full geometry optimization of all stationary points.[c] Single point calculations at the PM6 geometry.Calculated activation barriers of Spinosyn A formation.