A single amino acid determines the site of deprotonation in the active center of sesquiterpene synthases SbTPS1 and SbTPS2 from Sorghum bicolor

► We examined the reaction mechanism of Sorghum terpene synthases SbTPS1 and SbTPS2. ► The deprotonation reaction determines the different product specificity of SbTPS1/2. ► The pyrophosphate group probably acts as proton donor.