Regioselectivity and Deuterium Isotope Effects in Geraniol Hydroxylation by the Cytochrome P-450 Monooxygenase from Catharanthus roseus (L.) G. Don

Article abstract of DOI:10.1002/hlca.19860690822

The hydroxylation of geraniol (8) by cytochrome P-450 (P-450_Cath) from the subtropical plant Catharanthus roseus (L.) G.Don was optimised to give 8-hydroxygeraniol (9) as the single product in 35percent yield.Incubations of different (13)C- and (2)H-labelled geraniols revealed that H-abstraction is completely regioselective in favour of the CH3 group trans to the chain at C(6) of (8).An intramolecular isotope effect k_H/k_D = 8.0 was determined, suggesting that H-abstraction is one of the major rate-contributing steps; however, the intramolecular isotope effect was surprisingly inverse at low conversion k_H/k_D = 0.50, indicating the existence of rate-contributing steps preceding the first irreversible, isotope-sensitive reaction in the sequence.