生物化学第九讲 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月桂酸肉豆蔻酸棕榈酸硬脂酸花生酸木蜡酸棕榈油酸油酸亚油酸亚麻酸花生四稀酸6FAinfood(x%)Source月桂酸(12:0)棕榈酸硬脂酸Oleic(油酸)Linoleic(亚油酸)

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磷脂酰胆碱,PC,又称卵磷脂磷脂酰丝氨酸，PS磷脂酰甘油，

PG

磷脂酰肌醇（PI）心磷脂双磷脂酰甘油11SomeGlycerophospholipidshaveether-linkedfattyacidsfoundincentralnervoussystemandinheartmuscle.It’sresistanttophospholipases.(why?)activeatverylowconcentration(0.1nM)releasedfrombasophils（嗜碱白细胞）缩醛磷脂血小板激活因子12Sphingolipids(神经)鞘氨醇13SimilaritiesbetweenPG&SM14神经酰胺(神经)鞘磷脂(SM)脑苷脂神经节苷脂15SphingolipidsatCellSurfaceareSitesofBiologicalRecognitionABObloodgroupsWhichlipid?16(神经酰胺)17GalactolipidsandSulfolipidsinChloroplasts184.CholesterolRolesofcholesterolinmammals (i)structuralcomponentofplasmamembraneandmodulatesmembranefluidity(ii)precursorofsteroidhormonesandbileacids

Rarelyfoundinplants,neverinbacteriaSteroidsandlipidvitaminescanbeclassifiedaspolyprenylcompounds19Cholesterol20ArchaebacteriaContainUniqueMembraneLipidsTheyliveinextremeconditions—hightemperatures(boilingwater),lowpH,highionicstrength.Theyhavemembranelipidscontaininglong-chain(32carbons)branchedhydrocarbonslinkedateachendtoglycerol.Theselinkagesarethroughetherbonds,whicharemuchmorestabletohydrolysisatlowpHandhightemperaturethanaretheesterbondsfoundinthelipidsofeubacteriaandeukaryotes.Atypicalmembranelipidofarchaebacteria21Phospholipidsaredegradedinlysosomes22SphingolipidsarealsodegradedinlysosomesTay-Sachsdisease:泰-萨二氏病，家族黑蒙性白痴；下图为婴儿患者脑细胞电镜照片23§9Lipids

§9.1Storagelipids§9.2Structurallipidsinmembranes

§9.3Lipidsassignals,cofactors,andpigments§9.4Separationandanalysisoflipids24Lipidsassignals,cofactors,andpigmentsPhosphatidylinositols(磷脂酰肌醇):细胞内信号转导Eicosanoids(廿烷类)：旁细胞信号转导Steroidhormones

(固醇类激素)：组织、器官间信号转导FatsolubleVitamins25磷脂酰肌醇:细胞内信号转导26Prostaglandins(前列腺素类)

:PGE;PGFThromboxanes(凝血噁烷类)

:由platelets产生，促进bloodclots形成.Leukotrienes(白细胞三烯类)

:过量会引起哮喘发作Eicosanoids(廿烷类)：旁细胞信号转导27(花生四烯酸)前列腺素类白细胞三烯类凝血噁烷类28环加氧酶29AspirinandIbuprofenbelongtoNon-SteroidalAnti-InflammatoryDrugs,NSAIDs.Ibuprofen(布洛芬)inhibitsthesamestep,probablybymimickingthestructureofthesubstrateoranintermediateinthereaction.AspirininhibitsthecyclooxgenaseactivityofCOXbyacetylatinganessentialSerresidueontheenzyme.30Derivatesofsterols;Playimportantrolesingeneexpression;Sexhormonesandhormonesfromadrenalcortex;Prednisoloneandprednisonearesteroiddrugwithpotentantiinflammatoryactivities.Steroidhormones

(固醇类激素)：组织、器官间信号转导

睾丸酮雌二醇皮质(甾)醇,氢化可的松醛固酮脱氢皮质(甾)醇强的松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