生物化學(xué)第九講 Lipids

§9Lipids

§9.1Storagelipids§9.2Structurallipidsinmembranes

§9.3Lipidsassignals,cofactors,andpigments§9.4

Separationandanalysisoflipids1StoragelipidsTriacylglycerolsWaxesfattyacids(C14-36)Alcohols(C16-30)+Highmeltingpoints(60-100

C)Energystorage(Plankton,浮游生物)Waterrepellant(birdsandplants)2FatcellofpigFatdropletsPlantseedcellStoredoilbodies3Triacontanoylpalmitate(majorcomponentofbeeswax)(三十烷醇/蜂花醇)4SpermWhales:FatheadsoftheDeepWhy?(Triacylglycerols+Waxes)5月桂酸肉豆蔻酸棕櫚酸硬脂酸花生酸木蠟酸棕櫚油酸油酸亞油酸亞麻酸花生四稀酸6FAinfood(x%)Source月桂酸(12:0)棕櫚酸硬脂酸Oleic(油酸)Linoleic(亞油酸)

肉豆蔻酸(14:0)(16:0)(18:0)(18:1)(18:2)Beef5 26-3220-2537-432-3Milk 5 12333Coconut74 1027Corn 8-123-419-2434-62Olive 9 284 4Palm 39 4 408Soybean 9 6 2052Sunflower 6 1 21667§9Lipids

§9.1Storagelipids§9.2Structurallipidsinmembranes

§9.3Lipidsassignals,cofactors,andpigments§9.4

Separationandanalysisoflipids8SphingolipidsinChloroplastsinArchaebacteria9

Glycerophospholipids(majorlipidinmembranes)10磷脂酰乙醇胺,PE磷脂酰膽堿,PC,又稱(chēng)卵磷脂磷脂酰絲氨酸，PS磷脂酰甘油，

PG

磷脂酰肌醇（PI）心磷脂雙磷脂酰甘油11SomeGlycerophospholipidshaveether-linkedfattyacidsfoundincentralnervoussystemandinheartmuscle.It’sresistanttophospholipases.(why?)activeatverylowconcentration(0.1nM)releasedfrombasophils（嗜堿白細(xì)胞）縮醛磷脂血小板激活因子12Sphingolipids(神經(jīng))鞘氨醇13SimilaritiesbetweenPG&SM14神經(jīng)酰胺(神經(jīng))鞘磷脂(SM)腦苷脂神經(jīng)節(jié)苷脂15SphingolipidsatCellSurfaceareSitesofBiologicalRecognitionABObloodgroupsWhichlipid?16(神經(jīng)酰胺)17GalactolipidsandSulfolipidsinChloroplasts184.CholesterolRolesofcholesterolinmammals (i)structuralcomponentofplasmamembraneandmodulatesmembranefluidity(ii)precursorofsteroidhormonesandbileacids

Rarelyfoundinplants,neverinbacteriaSteroidsandlipidvitaminescanbeclassifiedaspolyprenylcompounds19Cholesterol20ArchaebacteriaContainUniqueMembraneLipidsTheyliveinextremeconditions—hightemperatures(boilingwater),lowpH,highionicstrength.Theyhavemembranelipidscontaininglong-chain(32carbons)branchedhydrocarbonslinkedateachendtoglycerol.Theselinkagesarethroughetherbonds,whicharemuchmorestabletohydrolysisatlowpHandhightemperaturethanaretheesterbondsfoundinthelipidsofeubacteriaandeukaryotes.Atypicalmembranelipidofarchaebacteria21Phospholipidsaredegradedinlysosomes22SphingolipidsarealsodegradedinlysosomesTay-Sachsdisease:泰-薩二氏病，家族黑蒙性白癡；下圖為嬰兒患者腦細(xì)胞電鏡照片23§9Lipids

§9.1Storagelipids§9.2Structurallipidsinmembranes

§9.3Lipidsassignals,cofactors,andpigments§9.4Separationandanalysisoflipids24Lipidsassignals,cofactors,andpigmentsPhosphatidylinositols(磷脂酰肌醇):細(xì)胞內(nèi)信號(hào)轉(zhuǎn)導(dǎo)Eicosanoids(廿烷類(lèi))：旁細(xì)胞信號(hào)轉(zhuǎn)導(dǎo)Steroidhormones

(固醇類(lèi)激素)：組織、器官間信號(hào)轉(zhuǎn)導(dǎo)FatsolubleVitamins25磷脂酰肌醇:細(xì)胞內(nèi)信號(hào)轉(zhuǎn)導(dǎo)26Prostaglandins(前列腺素類(lèi))

:PGE;PGFThromboxanes(凝血噁烷類(lèi))

:由platelets產(chǎn)生，促進(jìn)bloodclots形成.Leukotrienes(白細(xì)胞三烯類(lèi))

:過(guò)量會(huì)引起哮喘發(fā)作Eicosanoids(廿烷類(lèi))：旁細(xì)胞信號(hào)轉(zhuǎn)導(dǎo)27(花生四烯酸)前列腺素類(lèi)白細(xì)胞三烯類(lèi)凝血噁烷類(lèi)28環(huán)加氧酶29AspirinandIbuprofenbelongtoNon-SteroidalAnti-InflammatoryDrugs,NSAIDs.Ibuprofen(布洛芬)inhibitsthesamestep,probablybymimickingthestructureofthesubstrateoranintermediateinthereaction.AspirininhibitsthecyclooxgenaseactivityofCOXbyacetylatinganessentialSerresidueontheenzyme.30Derivatesofsterols;Playimportantrolesingeneexpression;Sexhormonesandhormonesfromadrenalcortex;Prednisoloneandprednisonearesteroiddrugwithpotentantiinflammatoryactivities.Steroidhormones

(固醇類(lèi)激素)：組織、器官間信號(hào)轉(zhuǎn)導(dǎo)

睪丸酮雌二醇皮質(zhì)(甾)醇,氫化可的松醛固酮脫氫皮質(zhì)(甾)醇強(qiáng)的松31FatsolubleVitaminsvitaminsA,D,E,KLongchainpolyunsaturateshydrocarbonsattachedto1or2benzeneringsVitaminA(retinol)storedinliverprecursor:carotenedeficiency:nightblindnessVitaminDformedfromprecursorinskinbyUVregulatesCadepositiondeficiency:rickets323334ActiveVitD3VitD3isformedinskin1,25-dihydroxyVitD3isbiologicalactive;Itregulatesgeneexpression,e.g.turningonthesynthesisofanintestinalCa2+bindingprotein.35VitaminsEandKandLipidQuinonesareoxidation-reductioncofactorsVitE:

biologicalantioxidants;VitK:undergoesacycleofoxidationandreduction;duringtheformationofactiveprothrombin;Warfarin:syntheticcompoundthatinhibitstheformationofactiveprothrombin;Ubiquinone(coenzymeQ)andplastoquitone:

isoprenoidsthatfunctionaslipophilicelectroncarriersintheoxidation-reductionreactionsthatdriveATPsynthesisinmitochondriaandchloroplasts,respectively.

36Activesugarprecursors37RolesofLipidsEnergystorage(fattyacids,triacylglycerols)Structuralelements(phospholipids,cholesterol)Hormones(sexhormonese.g.Estrogen)Enzymecofactors(coenzymeA)Electroncarriers(co