Isolated from Abies grandis (grand fir) . This class I enzyme forms about equal proportions of abietadiene, levopimaradiene and neoabietadiene. See also EC 4.2.3.18, abieta-7,13-diene synthase and EC 4.2.3.32, levopimaradiene synthase. An X-ray study of this multifunctional enzyme showed that the class I activity is in the alpha domain, while (+)-copalyl diphosphate synthase activity (EC 5.5.1.12, a class II activity) is in the beta and gamma domains . In Pinus taeda (loblolly pine) the major product is levopimaradiene, with less abietadiene and neoabietadiene .
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The enzyme appears in viruses and cellular organisms
Isolated from Abies grandis (grand fir) [1]. This class I enzyme forms about equal proportions of abietadiene, levopimaradiene and neoabietadiene. See also EC 4.2.3.18, abieta-7,13-diene synthase and EC 4.2.3.32, levopimaradiene synthase. An X-ray study of this multifunctional enzyme showed that the class I activity is in the alpha domain, while (+)-copalyl diphosphate synthase activity (EC 5.5.1.12, a class II activity) is in the beta and gamma domains [2]. In Pinus taeda (loblolly pine) the major product is levopimaradiene, with less abietadiene and neoabietadiene [3].
the enzyme converts geranylgeranyl diphosphate and the intermediate (+)-copalyl diphosphate to a nearly equal mixture of abietadiene (31%), levopimaradiene (34%), and neoabietadiene (28%), as well as to three minor products pimara-8(14),15-diene (3%), palustradiene (2%), and sandaracopimaradiene (2%)
abietadiene synthase catalyzes the cyclization and rearrangement of (E,E,E)-geranylgeranyl diphosphate to a mixture of abietadiene double-bond isomers. The enzyme is bifunctional: Protonation across the terminal 14-15 double bond of (E,E,E)-geranylgeranyl diphosphate followed by bicyclization and deprotonation, produces the stable intermediate (+)-copalyl diphosphate (CPP). Then the enzyme ionizes CPP to promote cyclization to the tricyclic perhydrophenanthrene backbone. However, this cyclization is further coupled to a 1,2-methyl migration, by means of intramolecular proton transfer within a pimarenyl intermediate, to generate the C13 isopropyl group characteristic of the abietane skeleton. Finally, deprotonation of the resulting abietenyl carbocation at one of three alternative positions (C7, C12, or C15) leads to the three principal olefin products abieta-7(8),13(14)-diene (abietadiene), abieta-8(14),12(13)-diene (levopimaradiene), and abieta-8(14)-13(15)-diene (neoabietadiene), respectively, as a function of pH
the enzyme forms levopimaradiene (45.2%), abietadiene (27.6%), palustradiene (4.5%), and neoabietadiene (22.4%) from geranylgeranyl diphosphate, but shows no activity with geranyl diphosphate or farnesyl diphosphate
abietadiene synthase catalyzes the committed step in resin acid biosynthesis by catalyzing the cyclization and rearrangement of (E,E,E)-geranylgeranyl diphosphate to a mixture of abietadiene double-bond isomers. The enzyme is bifunctional: Protonation across the terminal 14-15 double bond of (E,E,E)-geranylgeranyl diphosphate followed by bicyclization and deprotonation, produces the stable intermediate (+)-copalyl diphosphate (CPP). Then the enzyme ionizes the CPP to promote cyclization to the tricyclic perhydrophenanthrene backbone. However, this cyclization is further coupled to a 1,2-methyl migration, by means of intramolecular proton transfer within a pimarenyl intermediate, to generate the C13 isopropyl group characteristic of the abietane skeleton. Finally, deprotonation of the resulting abietenyl carbocation at one of three alternative positions (C7, C12, or C15) leads to the three principal olefin products abieta-7(8),13(14)-diene (abietadiene), abieta-8(14),12(13)-diene (levopimaradiene), and abieta-8(14)-13(15)-diene (neoabietadiene), respectively
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-80°C, 10 mM Bis-Tris, pH 6.8, 10% (v/v) glycerol, 150 mM KCl, 10 mM MgCl2, and 5 mM dithiothreitol, several months, without significant loss of activity
Diterpene resin acid biosynthesis in loblolly pine (Pinus taeda): Functional characterization of abietadiene/levopimaradiene synthase (PtTPS-LAS) cDNA and subcellular targeting of PtTPS-LAS and abietadienol/abietadienal oxidase (PtAO, CYP720B1)
4.2.3.132 neoabietadiene synthase
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