Pichersky E, Lewinsohn E, Croteau R
Biology Department, University of Michigan, Ann Arbor 48109.
Arch Biochem Biophys. 1995 Feb 1;316(2):803-7. doi: 10.1006/abbi.1995.1107.
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.
S-芳樟醇是布鲁氏克拉花（Clarkia breweri Grey [Green]）花朵释放出的挥发性物质之一，用于吸引其蛾类传粉者。S-芳樟醇合酶能立体选择性地将普遍存在的C10中间体香叶基焦磷酸（GPP）转化为S-芳樟醇，在刚开放花朵的柱头中含量丰富，通过阴离子交换和羟基磷灰石色谱法将其纯化至>95%的纯度。S-芳樟醇合酶与其他单萜合酶一样可操作溶解，对香叶基焦磷酸的Km值为0.9微摩尔，对二价金属辅因子有严格要求，偏好Mn2+（Km = 45微摩尔），最佳pH值为7.4。通过凝胶渗透色谱法和聚丙烯酰胺凝胶电泳测定，该酶以76 +/- 3 kDa的单体形式具有活性。S-芳樟基焦磷酸酯和R-芳樟基焦磷酸酯都不是布鲁氏克拉花S-芳樟醇合酶的底物，尽管这种叔烯丙基焦磷酸酯在许多植物物种中是由香叶基焦磷酸生物合成环状单萜的结合中间体，在这些植物中它也作为替代底物。
