Pinene synthases

SCHWAB, W., WILLIAMS, D. C DAVIS, E. M., CROTEAU, R Mechanism of monoterpene cyclization Stereochemical aspects of the transformation of noncyclizable substrate analogs by recombinant (-)-limonene synthase, (+)-bomyl diphosphate synthase, and (-)-pinene synthase, Arch. Biochem. Biophys., 2001, 392, 123-136. 

BOHLMANN, J., STEELE, C. L., CROTEAU, R. Monoterpene synthases from grand fir (Abies grandis) - cDNA isolation, characterization, and functional expression of myreene synthase, (-X4S)-limonene synthase, and (->-<1 S,5S)- pinene synthase, J. Biol. Chem., 1997, 272, 21784-21792. 

Lu, S., Xu, R., Jia, J.W., Pang, J., Matsuda, S.P. and Chen, X.Y (2002) Gloning and functional characterization of a beta-pinene synthase from Artemisia annua that shows a circadian pattern of expression. Plant Physiol., 130,477-86. 

McKay, S.A., Hunter, W.L., Godard, K.A., Wang, S.X., Martin, D.M., Bohlmann, J. and Plant, A.L. (2003) Insect attack and wounding induce traumatic resin duct development and gene expression of (—)-pinene synthase in Sitka spruce. Plant Physiol, 133, 368-78. 

Phillips, M.A., Wildung, M.R., Williams, D.C., Hyatt, D.C. and Croteau, R. (2003) cDNA isolation, functional expression, and characterization of (-l-)-alpha-pinene synthase and (—)-alpha-pinene synthase from loblolly pine (Pinus taeda) stereocontrol in pinene biosynthesis. Arch. Biochem. Biophys., 411, 267-76. 

The deuterium labelling established that the y, 5-unsaturated, nitrile 241 equilibrates at room temperature with the iV-allylketene imine 242 through an intramolecular rearrangement mechanism. Deuterium has been applied in the study of the novel palladium(0)-catalysed cyclization of 2,7-octadienyl carbonate containing an allylsilane moiety, 243, to product 244 (in 89%) and some 245 in the presence of phosphite 246 (equation 99). Intramolecular KlEs (Ah/Ad =3.0 and 3.5) have been observed in a bicyclic olefin formation (monoterpinene biosynthesis from [1- H,4- H2]- and [10- H2]-geranyl pyrophosphates) catalysed by pinene synthases from sage (Salvia officinalis). ... 

More than a dozen cDNAs encoding monoterpene synthases from a range of plant sources have now been isolated [22, 32-36]. The corresponding recombinant enzymes generate a diverse set of products and provide an exceptional set of catalysts for the detailed study of structure-function relationships in monoterpene cyclization. However, it was earher work with native synthases that first allowed definition of the cyclization reaction [ 15]. Thus, the stereochemical model for monoterpene cyclization was developed largely from studies with the bicyclic monoterpene cyclases (-i-)- and (-)-bornyl diphosphate synthases, (-1-)-and (-)-pinene synthases, and (-)-e do-fenchol synthase. It was also the purification of several native monoterpene synthases that gave the first indication that... 

Scheme 11.45. Some of the monoterpene rearrangement products for which some specific synthases have been found [e.g., (-)-en

To date over 30 plant terpenoid synthases have been cloned as cDNAs, and many of these were found to encode enzymes of secondary metabolism (43). Isolation and analysis of six genomic clones encoding monoterpene ((—)-pinene and (—)-limonene), sesquiterpene ((E)-a-bisabolene and S-selinene) and diterpene (abietadiene) synthases from Abies grandis, and a diterpene (taxadiene) synthase from Taxus brevifolia have been reported (44). Overexpression of a cotton farnesyl diphosphate synthase (EPPS) in transgenic Artemesia annua has resulted in 3- to 4-fold increase in the yield of the sesquiterpenoid anti-malarial drug, artemisinin, in hairy roots (45). 

The biosynthetic route to menthol, starts from isopentenyl- and dimethylallyl diphosphate, which in the case of mint derive from the triose-pyruvate pathway, and consists of eight discrete steps (see also section 7.1.2). This route was established by feeding experiments with radio-lahelled intermediates and cell-free enzyme studies. [110] Condensation of isopentenyl- and dimethylallyl diphosphate gives geranyl diphosphate, which is cyclised to (-)-limonene. Both steps are Mg +-dependent. By-products of the cyclisation are around 2 % of myrcene and both, a- and y -pinene. The limonene synthases in Mentha piperita and Mentha spicata are identical, which shows how closely related to each other the species are. 

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