Purification and characterization of S-linalool synthase, an enzyme involved in the production of floral scent in Clarkia breweri.
S-Linalool is one of the volatiles emitted by Clarkia breweri Grey [Green] flowers to attract its moth pollinator. S-Linalool synthase, the enzyme that stereoselectively converts the ubiquitous C10 intermediate GPP to S-linalool, is abundant in stigmata of freshly opened flowers, and it was purified to > 95% homogeneity by anion-exchange and hydroxyapatite chromatography. S-Linalool synthase is operationally soluble as are other monoterpene synthases, has a Km of 0.9 microM for geranyl pyrophosphate, exhibits a strict requirement for a divalent metal cofactor with a preference for Mn2+ (Km = 45 microM), and shows an optimal pH of 7.4. The enzyme is active as a monomer of 76 +/- 3 kDa as determined by gel permeation chromatography and polyacrylamide gel electrophoresis. Neither S- nor R-linalyl pyrophosphates are substrates for the C. breweri S-linalool synthase, although this tertiary allylic pyrophosphate ester is a bound intermediate in the biosynthesis of cyclic monoterpenes from geranyl pyrophosphate in many plant species, where it also serves as an alternate substrate.
Pichersky
E
E
Biology Department, University of Michigan, Ann Arbor 48109.
Lewinsohn
E
E
Croteau
R
R
D000080462:Acyclic Monoterpenes; D006836:Hydro-Lyases / Q000302:isolation & purification / Q000378:metabolism*; D039821:Monoterpenes; D009812:Odorants; D018520:Plant Shoots / Q000201:enzymology*; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D013729:Terpenes / Q000378:metabolism*
D000080462:Acyclic Monoterpenes; D039821:Monoterpenes; D011106:Polyisoprenyl Phosphates; D013729:Terpenes; C015234:geranyl pyrophosphate; C018584:linalool; D006836:Hydro-Lyases; C092055:S-linalool synthase