《厦大生化》课件

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1、Chapter26ThebiosynthesisofmembranelipidsandsteroidsFatssuchasthetriacylglycerolmoleculearewildlyusedtostoreexcessenergyforlateruseandtofulfillotherpurposes.26.1PhosphatidateisacommonintermediateinthesynthesisofphospholipidsandtriacylglycerolsGlycerolphosphateacyltransferase.Endoplasm

2、icreticulum/Outermitochondrialmembrane.Diglycerideacyltransferase.Triacylglcerolsynthetasecomplexinliver.26.1.1ThesynthesisofphospholipidsrequiresanactivatedintermediatePhospholipidsynthesis=thecombinationofadiacylglyceridewithanalcoholAnabolicreactionDiacylglyceroloralcoholshouldbea

3、ctivated.SynthesisfromanactivateddiacylglerolStructureofCDP-diacylglycerol.SynthesisformanactivatedalcoholInallofbiosyntheses,anactivatedintermediate(UDP-glucose,CDP-diacylglycerol,CDP-alcohol)isformedfromaphosphorylatedsubstrate(glucose-1-phosphate,phosphatide,phosphorylalcohol)anda

4、nucleosidetriphosphate.Theactivatedintermediatethenreactswithahydroxylgroup(theterminusofglycogen,thesidechainofserine,oradiacylglycerol).26.1.2PlasmalogensandotheretherphospholipidsaresynthesizedfromdihydroxyacetonephosphateSynthesisofanetherphospholipid.26.1.3Sphingolipidsaresynthe

5、sizedfromceramide鞘氨醇Synthesisofsphingolipids.神经酰胺葡萄糖脑苷脂神经节苷脂鞘磷脂GangliosideGM1.半乳糖唾液酸N-乙酰半乳糖胺葡萄糖26.1.4RespiratorydistresssyndromeandTay-SachsdiseaseresultfromthedisruptionoflipidmetabolismTay-Sachsdisease（泰萨氏幼年黑朦白痴症）(1)A1-year-oldinfantwithTay-Sachsdisease.(2)Electronmicrographofaport

6、ionofanaffectedbraincell,showingtheabnormalgangliosidedepositsinthelysosomes.26.2CholesterolissynthesizedfromacetylcoenzymeAinthreestagesLabelingofcholesterol.26.2.1Thesynthesisofmevalonate,whichisactivatedasisopentenylpyrophosphate,initiatesthesynthesisofcholesterolFatesof3-hydroxy-

7、3-methylglutarylCoA.二羟甲基戊酸Synthesisofisopentenylpyrophosphate.Squalenesynthesis.异戊二烯基转移酶焦磷酸牻牛儿酯26.2.2SqualenecyclizestoformcholesterolSqualenecyclization.Oxidosqualenecyclase.Cholesterolformation.26.3ThecomplexregulationofcholesterolbiosynthesistakesplaceatseverallevelsHMG-CoAreducta

8、se.3-hydroxy