生物化学 Chap 9 lipid metabolism.ppt

《生物化学 Chap 9 lipid metabolism.ppt》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、Chap9lipidmetabolismCatabolismoffat/triglycerideAnabolismoffat/triglycerideSection1CatabolismoftriglycerideHydrolysisoftriglycerideGlycerolbreakdownGlycerolkinase3-PhosphoglyceroldehydrogenaseFattyacidbreakdown(ß-oxidation/ß-氧化)Fattyacidbreakdownbringsabouttheoxidationoflong-chainaci

2、dswiththeproductionofenergy(ATP).Fattyacidbreakdownoccursinthecytosolofprokaryotesandinthemitochondriaofeukaryotes.Location:Thiokinase(硫激酶,alsocalledacylCoAsynthase)Beforeenteringthemitochondria,thefattyacidisactivatedbyformingathioesterlinkwithCoA.Step1ActivationStep2Transportintomi

3、tochondriaLongchainacylCoAscannotcrosstheinnermitochondriamembrane,andrequireaspecifictransportmechanism.Toachievethis,thelongchainacylCoAsareconjugatedtothepolarcarnitine(肉毒碱，catalyzedbycarnitineacyltransferase)。R-C-SCoAOH-SCoAcytosolcarnitinecarnitineacyltransferaseⅠR-C-carintineOIn

4、nermembranemitochondriatranslocaseR-C-carintineOcarnitineH-SCoAR-C-SCoAOmitochondriaⅡStep3β-oxidationpathwayHSCoArepeatingsequenceoffourreactions:oxidation(byFAD)Hydrationoxidation(byNAD+)thiolysis.Thesefourreactionsformone‘round’offattyaciddegradationtoremovetwo-carbonunitsintheformo

5、facetylCoA.Thus,C16saturatedfattyacid,suchaspalmitate(棕榈酸),wouldbecompletelydegradedinto:eightmoleculesofacetylCoAbysevenroundsofβ-oxidation.EnergyyieldOnemoleculeofsaturatedfattyacidwith18carbonatoms(C18)iscompletelyoxidized,thenhowmanyATPwillbereleased?Key:146ATPActivation:ATPAMP-2A

6、TPOnecycleβ-oxidation:1FADFADH21NAD+NADH+2ATP+3ATPOneacetylCoA:TCA+12ATP+5ATP8×5+12×9-2=146ATPOxidationofodd-chainfattyacidSection2Anabolismoftriglyceridesynthesisoftriglycerideincludethreeparts:GlycerolsynthesisFattyacidsynthesisTriglyceridesynthesisGlycerolsynthesisFattyacidsynthesi

7、sincytosol(胞浆合成体系)Forsynthesisoffattyacidwithnolessthan16carbonatomsInmitochondria(线粒体加长体系)forelongationoffattyacidsACP:acylcarrierproteinincytosolInmitochondriaComparisonoffattyacidoxidationandsynthesisb-oxidationFattyacidsynthesisIncytosolInmitochondriaCarrierforacylactivation(活化酰基载

8、体)CoA