Lipidmetabolism脂类合成

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1、8.LipidmetabolismKeynotesStructuresandrolesoffattyacidsFattyacidbreakdownFattyacidsynthesisTriacylglycerols8.1StructuresandrolesoffattyacidsFattyacidshavealonghydrocarbonchainwithaterminalcarboxylicacidgroup.Mostfattyacidshaveanevennumberofcarbonatomsinanunbranchedchain.Saturatedfattyacidsh

2、avenodoublebondsbetweenthecarbonatoms,whereasmono-andpolyunsaturatedfattyacidshaveoneormoredoublebonds.Stearicacid(b)Fattyacidshavefourmajorbiologicalroles:1)Theyarecomponentsofmembranes(glycerophospholipidsandsphingolipids)2)Severalproteinsarecovalentlymodifiedbyfattyacids.3)Theyactasenerg

3、ystores(triacylglycerols)andfuelmolecules.4)Fattyacidderivativesserveashormonesandintracellularsecondmessengers.8.2FattyacidbreakdownOverviewActivationTransportintomitochondriaβ-oxidationpathwayEnergyyieldKetonebodies1.overviewFattyacidbreakdownbringsabouttheoxidationoflong-chainfattyacidsw

4、iththeproductionofenergyintheformofATP.ThefattyacidsarefirstconvertedtotheiracylcoenzymeAderivativesandthendegradedbythesuccessiveremovaloftwo-carbonunitsfromtheendofthefattyacidasacetylCoA.IncytosolAcylCoAsynthetase2.FattyacidactivationRCOOH+CoA—SHRCO~SCoAAcylCoAsynthetaseATPAMP+PPiMg2+H2O

5、2PithereactionisirreversiblefattyacidacylCoA3.TransportintomitochondrialongerchainacylCoAsdonotreadilycrosstheinnermitochondrialmembrane,andrequireaspecifictransportmechanism.RCO-SCoACoA-SHtransferase(CH3)3N+-CH2CH-CH2COOHOHcarnitine(CH3)3N+CH2CHCH2COOHRCO-OacylcarnitineR-COSCoAH-SCoAcarnit

6、ineR-CO-carnitineR-CO-carnitineH-SCoAcarnitineR-COSCoAtransferaseⅠβ-oxidationtransferaseⅡInnermitochondrialmembrane4.β-OxidationpathwayOxidation(byFAD)HydrationOxidation(byNAD+)Thiolysis①oxidationacylCoAdehydrogenaseFADFADH2②hydrationRCH2CCCO~CoAHHtrans2-enoylCoAenoylCoAhydrataseH2OOHRCH2C

7、HCH2CO~SCoA3-hydroxyacylCoA1.5ATPrespiratorychainＯR-CH2-CH2C-SCoA

8、

9、OHRCH2CHCH2CO~SCoA③oxidationNAD+NADH+H+dehydrogenase④thiolysisCH3CO~SCoARCH2CO~SCoA（1）（2）（3）（4）3-ketoacylCoARCH2C~SCoAOCH2COCoA-SHketothiolase2.5ATPrespiratorychainroundreactionOxidationo