4.2.3.86 additional information molecular modelling of the two enzymes, selinene synthase (EC 4.2.3.86) and alpha-guayene synthase (EC 4.2.3.87) based on the TEAS template structure reveals that two of the varying amino acid positions are directly located in the active site, proximal to the location of FPP binding and subsequent catalysis, while the other four amino acid differences are located more peripherally, structure-function analysis. The S414 and M530 residues both contribute to the internal binding site of farnesyl diphosphate and are located on separate alpha-helices that contribute to the formation of the internal cavity comprising the FPP substrate-binding site 748331 4.2.3.86 physiological function the enzyme produces alpha-guaiene, a precursor of rotundone 748331