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Sesquiterpene Cyclases Christianson et al. Curr. Opin. Struct. Biol. 1998, 695 (DOI)
Terpene Cyclases – Control of Cyclisation • Functional aspects of terpenoid cyclases: – Templating: Active site provides a template for a specific conformation of the flexible linear isoprenoid starting material. – Triggering: Cyclase initiates carbocation formation. • Metal-assisted leaving group departure (e.g. pyrophosphate ionization aided by Mg 2+ ) • C=C bond protonation (e.g. squalene-hopene cyclase, see later). • Epoxide protonation (e.g. oxidosqualene cyclase, see later). – Chaperoning: Chaperones conformations of carbocationic intermediates through the reaction sequence, ordinarily leading to one specific product. – Sequestering: Sequesters the carbocation intermediates by burying the substrate in a hydrophobic cavity that is generally solvent-inaccessible. Carbocations are concomitantly stabilized by the presence of aromatic residues in the active site that exert their effects via cation-π interactions RECALL: δ = δ δ δ on edges δ on faces – Adapted from: Christianson et al. Curr. Opin. Struct. Biol. 1998, 695 (DOI) • BUT: – individual terpene cyclases can give multiple products, see: Matsuda J. Am. Chem. Soc. 2007, 129, 11213 (DOI) R R R Enz cation - π stabilisation (~40-80 kJmol -1 )
Page 1 and 2: Biosynthesis - Inspiration for Drug
Page 3 and 4: Isoprenoids • isoprenoids are wid
Page 5 and 6: PO glycolysis CO 2 phosphoenol pyru
Page 7 and 8: Biosynthesis of IPP & DMAPP - via M
Page 9 and 10: Biosynthesis of IPP & DMAPP - via 1
Page 11 and 12: Linear C 5n ‘head-to-tail’ Pyro
Page 13 and 14: Monoterpenes from Rosemary & Thyme
Page 15 and 16: Monoterpenes - α-Terpinyl Cation F
Page 17 and 18: Apparently Irregular Monoterpenes
Page 19: Sesquiterpenes - Farnesyl Pyrophosp
Page 23 and 24: Aristolochene & 5-Epi-Aristolochene
Page 25 and 26: H Diterpenes - Geranylgeranyl Pyrop
Page 27 and 28: Diterpenes - Geranylgeranyl PP →
Page 29 and 30: Triterpenes - Squalene → 2,3-Oxid
Page 31 and 32: Oxidosqualene-Lanosterol Cyclase (O
Page 33 and 34: Lanosterol → Cholesterol - Oxidat
Page 35 and 36: Steroid Ring Cleavage - Vitamin D &
Page 37: PO glycolysis CO 2 phosphoenol pyru

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