Partial purification and characterization of two sesquiterpene cyclases from sage ( Salvia officinalis) which catalyze the respective conversion of farnesyl pyrophosphate to humulene and caryophyllene

Abstract

Humulene cyclase and caryophyllene cyclase, two enzymes which catalyze the cyclization of farnesyl pyrophosphate to the respective sesquiterpene olefins, have been partially purified from the supernatant fraction of a sage ( Salvia officinalis) leaf epidermis extract and separated from each other by a combination of hydrophobic interaction, gel filtration, and ion-exchange chromatography. The molecular weight of both cyclases was estimated by gel filtration to be 57,000, and both cyclases exhibited a pH optimum of 6.5 and preferred Mg 2+ ( K m ~ 1.5 mM) as the required divalent metal cation. Both enzymes possessed a K m of about 1.7 μ m for farnesyl pyrophosphate, were strongly inhibited by p-hydroxymercuribenzoate, and exhibited comparable sensitivities to a variety of other potential inhibitors. The properties of the two sesquiterpene olefin cyclases, which are the first from a higher plant source to be examined in detail, were very similar to each other and to other monoterpene, sesquiterpene, and diterpene cyclases previously described.