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MEVALONIC ACID PATHWAY

MEVALONIC ACID PATHWAY. TERPENES. THERE ARE TWO CARBONYL GROUPS IN THE 2-UNIT POLYKETIDE CHAIN. EITHER ONE CAN REACT. . 1. 2. - CO 2. LINEAR. BRANCHED. mevalonic acid. POLYKETIDE CHAINS. TERPENES. STEROIDS. ACETOGENINS. MEVALONIC ACID PATHWAY.

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MEVALONIC ACID PATHWAY

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  1. MEVALONIC ACID PATHWAY TERPENES

  2. THERE ARE TWO CARBONYL GROUPS IN THE 2-UNIT POLYKETIDE CHAIN EITHER ONE CAN REACT .. 1 2 - CO2 LINEAR BRANCHED mevalonic acid POLYKETIDE CHAINS TERPENES STEROIDS ACETOGENINS

  3. MEVALONIC ACID PATHWAY FORMATION OF MEVALONIC ACID FROM ACETYL UNITS NADPH 3 acetylCoA : : .. - NADPH H2O mevalonic acid (continued next slide)

  4. MEVALONIC ACID PATHWAY The isopentenyl and 3,3-dimethylallyl pyrophosphate intermediates ADP AMP :B-Enz 2 ATP mevalonic acid These five-carbon intermediates are responsible for the formation of all the terpenes. Enz-B: H+ IPP DMAPP 3,3-dimethylallyl pyrophosphate isopentenyl pyrophosphate

  5. TERPENES

  6. TERPENES The Czech chemist Leopold Ruzicka ( born 1887) showed that many compounds found in nature were formed from multiples of five carbons arranged in the same pattern as an isoprene molecule (obtained by pyrolysis of natural rubber). natural rubber head . D C tail C C C C isoprene isoprene unit He called these compounds “terpenes”.

  7. JOINING ISOPRENE UNITS individual isoprene units join head-to-tail Head-to-Tail an extra bond Tail-to-Tail The terms head-to-tail and tail-to-tail are often used to describe how the isoprene units are joined. larger terpenoid units dimerize tail-to-tail ….. explained later

  8. TERPENES CAN BE SHOWN TO BE FORMED FROM ISOPRENE UNITS head to tail limonene diagram showing how two isoprene units combine to form the limonene skeleton from lemon and orange peels

  9. CLASSIFICATION OF TERPENES TYPE OF NUMBER OF ISOPRENE TERPENE CARBON ATOMS UNITS one hemiterpene C5 two terpene C10 sesquiterpene C15 three diterpene C20 four sesterterpene C25 five triterpene C30 six eight C40 tetraterpene NOTE: hemi = half di = two sesqui = one and a half tri = three tetra = four

  10. SOME TERPENES (C10) geraniol menthol rose and other flowers peppermint camphor a-pinene camphor tree turpentine

  11. SESQUITERPENES guaiazulene geranium oil caryophyllene oil of cloves

  12. ….. more sesquiterpenes cedrene cedar wood oil longifolene pine species

  13. TRITERPENES TAIL-TO-TAIL ambrein ambergis

  14. All steroids are triterpenes but their skeletons have been rearranged so that they can not be analyzed into isoprene units. STEROIDS ARE TRITERPENES (C30) rearrangements in this area

  15. TETRATERPENE head-to-tail tail-to-tail head-to-tail b-carotene carrots

  16. HOW THE TERPENES ARE FORMED

  17. CONCATENATION OF C5 (ISOPRENE) UNITS DMAPP IPP C5 C10 HEAD :B C5 isopentenyl-PP 3,3-dimethylallyl-PP C10 TAIL geranyl-PP C15 C20 C15 farnesyl-PP C20 again geranyl-geranyl-PP EACH NEW UNIT IS JOINED HEAD-TO-TAIL

  18. C30 AND C40 UNITS ARE FORMED DIFFERENTLY Number Isoprene Class of Carbons Units Origin HEMITERPENES C5 1 IPP or DMAPP MONOTERPENES C10 2 geranyl-PP x2 SESQUITERPENES C15 3 farnesyl-PP x2 DITERPENES C20 4 geranyl-geranyl-PP SESTERTERPENE C25 5 uncommon TRITERPENES C30 6 2 x (farnesyl-PP) C35 7 uncommon TETRATERPENES C40 8 2 x (geranyl-geranyl-PP)

  19. DIMERIZATION OF C15 AND C20 UNITS TAIL rearrange TAIL dimerize Enz-B: H:- NADH NAD+ JOINED SYMMETRICALLY TAIL-TO-TAIL UNITS ARE JOINED TAIL-TO-TAIL

  20. COMMON TERPENOID SKELETONS TERPENES SESQUITERPENES HEMITERPENES C5 C10 C15 DITERPENES TRITERPENES C20 C30

  21. TERPENOIDS

  22. geranial b-myrcene geranium oil hops neral geraniol lemon oil geranium oil geranyl-PP (GPP) linalyl-PP (LPP) neryl-PP (NPP) citronellol rose oil citronellal a-terprneol linalool nerol citronella oil rose oil coriander oil

  23. OPP- methyl a-terpinyl cation or + ionize + + LPP 1,2-alkyl shift + + + - H+ b-pinene 1,2-alkyl shift H2O - H+ - H+ a-pinene + H2O borneol NADP+ camphene NADP+ camphor fenchone fenchol

  24. TAXOL H+ + + (+) + GGPP 3 100-yr-old trees = 1 g Used clinically in treatment of breast, ovarian, lung, head, neck cancers. Phe acetylCoA taxadiene many steps: oxidations, esterification Phe acetylCoA (taxol) paclitaxel Pacific Yew (bark) Phe

  25. ASSIGNMENTS Orange Problem Due in 10 days: Wednesday, Nov 14, 2007

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