中南大学 生物化学 考研课件 ch25 脂类生物合成 lipid biosynthesis

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1、BiochemistryForSpecialityofBiotechnologyorBioengineeringatCSUMr.XIAJinlanChapter25LipidbiosynthesisFattyacidsynthesisSynthesisofsaturatedfattyacidsSynthesisanddegradationoffattyacidstakeplaceindifferentplacesDifferencesbetweenfattyacidbreakdownandsynthesisBreakdownSynthesisSiteofactionsCyt

2、osolforprokaryotesMitochondriaforeukaryotesCytosolforbothprokaryotesandeukaryotesRoleofNADPHorNADHNADHproducedinb-oxidationUseNADPHasthereductantLinkageofFattyacidFattyacid-CoAFattyacid-acylcarrierproteinUseofenzyme(s)SeveralindividualseparateenzymesSeparateenzymesforplantsandbacteriaSingl

3、emultifunctionalenzymecomplex-fattyacidsynthaseforanimalsSaturatedfattyacid-CoAThegeneralreaction(forpalmiticacidsynthesis)Alternativelyexpressedas:Fattyacidissynthesizedfromacetyl-CoAincytosolInoneword:Wheredoestheacetyl-CoAcomefromandhowdoesittransfer?CytosolAcetyl-CoAAminoaciddegradatio

4、nMitochondrionAcetyl-CoAFattyacidoxidationGlycolysisPyruvatecytosolRequiredcytosolMTMTMT:mitochondrionCitrate-malate-pyruvateshuttleWhyismalonyl-CoAneeded?Howdoesitcommonlyform?Thefirststepistoformacetyl-and,malonyl-acylcarrierproteinAcetyltransacylaseisnothighlyspecific,butnotatmuchlowerr

5、ates;malonyltransacylaseisjustcontrary.StructuresofACPandCoA(CoASH)Acetyl-CoAcarboxylaseisBiotin-dependentanddisplaysping-pongkineticsThecarboxylationofbiotinThetranscarboxylationofbiotinThecarboxylationofacetyl-CoAInanimals,acetyl-CoAcarboxylaseisamultifunctionalproteinTheACCaseIsmodulate

6、dbyphosphorylationanddephosphorylationP808Alsoseep819MoreactiveformThen,howdoesthefattyacidchainelongateandIstherealsoacommoncycle?TheelongationcycleoffattyacidsynthesisThefinalproductoffattyacidsynthesisTotalcycles:7TheinitialandcontinuationreactionoffattyacidsynthesisForthefurthersynthes

7、isofC>16fattyacids,howdoesitprocess?CatalyzedbyenzymesonsmoothER(SER)Malonyl-CoA,ratherthanmalonyl-ACPasthetwo-carbondonorElongatedchainasCoAderivativeratherthanACPderivativeAdditionalelongationInERHowisthefattyacidsynthesisregulated?Thekeyenzyme:acetyl-CoAcar