Metabolism of monoterpenes: Demonstration of the hydroxylation of (+)-sabinene to (+)- cis-sabinol by an enzyme preparation from sage ( Salvia officinalis) leaves

A microsomal preparation from the epidermis of Salvia officinalis leaves catalyzed the NADPH- and O 2-dependent hydroxylation of the monoterpene olefin (+)-sabinene to (+)- cis-sabinol. The reaction catalyzed is a key step in the biosynthesis of C3-oxygenated thujane monoterpenes, and the hydroxylase is highly specific for (+)-sabinene as substrate. The hydroxylase from leaf homogenates was solubilized and characterized with regard to reaction conditions, inhibitors, and activators. Activity was partially inhibited by rabbit anti-rat cytochrome P-450 and by CO, and the latter inhibition was reversed by 450 nm light. A CO-difference spectrum and type I substrate binding spectrum were obtained. The hydroxylase meets most of the established criteria for a cytochrome P-450-dependent mixed function oxygenase and represents one of very few enzyme systems of this type to be isolated from leaves of a higher plant.