19 mutants of the cineole synthase of N. suaveolens were generated by site-directed mutagenesis in order to substitute the amino acids of the cineole synthase with amino acids of the equivalent position of the terpineol synthase of N. langsdorfii. The mutant enzyme F266S carrying a phenylalanine replacement by serine showed an inverted product spectrum compared to the wild type enzyme. Terpineol was the major compound in the product profile of the mutant F266S. It is hypothesized that the synthesis of cineole proceeds independent of terpineol and via α-terpinyl hydronium ion (Wise et al. 2002).