第二节 脂肪的分解代谢VIP免费

第二节脂肪的分解代谢二、甘油的代谢一、脂肪的动员三、脂肪酸的β-氧化四、脂肪酸的其他氧化方式五、酮体的生成和利用脂类的消化和吸收关键酶：激素敏感脂肪酶(hormone-sensitivelipase,HSL)一、脂肪的动员一、脂肪的动员RCCHCH2CH2OCROOCOROHOCHCH2CH2OHOHRCOHOO3+激素敏感脂肪酶H2O3+脂肪甘油脂肪酸脂解激素:能促进脂肪动员的激素，如胰高血糖素、肾上腺素、去甲肾上腺素等。对抗脂解激素因子:抑制脂肪动员，如胰岛素、前列腺素E2等。通过血液循环进入其他组织氧化供能运到肝脏、肾脏进入糖代谢二、甘油的代谢二、甘油的代谢组织：除脑组织外,大多数组织均可进行，其中肝、肌肉最活跃。亚细胞：胞液、线粒体三、脂肪酸的三、脂肪酸的ββ--氧化氧化(β-oxidation)1.脂肪酸的活化——脂酰CoA的生成（胞液）脂酰CoA合成酶(acyl-CoAsynthetase)存在于内质网及线粒体外膜上++CoA-SHCoA-SH脂肪酸RCHRCH22CHCH22CC--OHOHOO=OO=脂酰~SCoARCHRCH22CHCH22CC~SCoA~SCoAOO=OO=脂酰CoA合成酶ATPAMP+PPi2.脂酰CoA进入线粒体肉碱（carnitine）肉碱脂酰转移酶（carnitineacyltransferase）脂酰基肉碱肉碱脂酰转移酶ⅠL-肉碱Ⅱ肉碱脂酰转移酶Ⅱ3.脂肪酸的β-氧化脱氢加水再脱氢硫解脂酰CoAL-β-羟脂酰CoAβ-酮脂酰CoA脂酰CoA+乙酰CoA脂酰CoA脱氢酶Δ2-反烯脂酰CoAL-β-羟脂酰CoA脱氢酶NAD+NADH+H+Δ2--烯脂酰CoA水合酶H2OFADFADH2β-酮脂酰CoA硫解酶CoA-SHRCH=CHC~SCoAβαO=RCH=CHC~SCoAβαO=O=RCH2CH2C~SCoAO=O=RCHOHCH2C~SCoAβαO=O=RCOCH2C~SCoAβαO=O=RC~SCoA+CH3CO~SCoAO=O=棕榈酰CoAL-β-羟脂酰CoAβ-酮脂酰CoA14C脂酰CoA+乙酰CoAΔ2-反烯脂酰CoACH3(CH2)7CH2CH2CH2CH2CH2CH2CH2COSCoACH3(CH2)7CH2CH2CH2CH2CH2COSCoACH3COSCoACH3(CH2)7CH2CH2CH2COCoACH3COSCoACH3(CH2)7CH2COSCoACH3COCoACH3COSCoA55脂酰CoA脱氢酶L-β-羟脂酰CoA脱氢酶NAD+NADH+H+Δ2-烯脂酰CoA水合酶2H2OFADFADH2β-酮脂酰CoA硫解酶CoA-SH脂酰CoA合成酶肉碱转运载体ATPCoASHAMPPPiH2O呼吸链1.5ATPH2O呼吸链2.5ATP线粒体膜TAC脂肪酸RCHRCH22CHCH22CC--OHOHOO=OO=RCH=CHC~SCoAβαO=RCH=CHC~SCoAβαO=O=RCH2CH2C~SCoAO=O=RCHOHCH2C~SCoAβαO=O=RCOCH2C~SCoAβαO=O=RC~SCoA+CH3CO~SCoAO=O=RCH2CH2C~SCoAO=O=活化：消耗2个高能磷酸键β-氧化每轮循环四个步骤：脱氢、水化、再脱氢、硫解产物：1分子乙酰CoA1分子少两个碳原子的脂酰CoA1分子FADH21分子NADH+H+4.脂肪酸氧化的能量生成——以16碳软脂肪酸的氧化为例7轮循环产物：8分子乙酰CoA7分子NADH+H+7分子FADH2能量计算：生成ATP8×10+7×2.5+7×1.5=108净生成ATP108–2=106脂肪酸活化过程中消耗2个高能磷酸键丙酰CoA羧化酶（ATP、生物素）丙酰-CoAD-甲基丙二酸单酰-CoA甲基丙二酸单酰-CoA差向异构酶L-甲基丙二酰CoA琥珀酰CoA甲基丙二酸单酰-CoA变位酶奇数碳原子脂肪酸的氧化奇数碳脂肪酸IleMetValTACFatBearsCarryOutβOxidationinTheirSleepAlthoughexpendingabout25,000kJ/day(6,000kcal/day),thebeardoesnoteat,drink,urinate,ordefecateformonthsatatime.Agrizzlybearpreparesitshibernationnest,neartheMcNeilRiverinCanada.Experimentalstudieshaveshownthathibernatinggrizzlybearsusebodyfatastheirsolefuel.Fatoxidationyieldssufficientenergyformaintenanceofbodytemperature,activesynthesisofaminoacidsandproteins,andotherenergy-requiringactivities,suchasmembranetransport.Fatoxidationalsoreleaseslargeamountsofwater,asdescribedinthetext,whichreplenisheswaterlostinbreathing.Theglycerolreleasedbydegradationoftriacylglycerolsisconvertedintobloodglucosebygluconeogenesis.Bearsstoreanenormousamountofbodyfatinpreparationfortheirlongsleep.Anadultgrizzlyconsumesabout38,000kJ/dayduringthelatespringandsummer,butaswinterapproachesitfeeds20hoursaday,consumingupto84,000kJdaily.Thischangeinfeedingisaresponsetoaseasonalchangeinhormonesecretion.Largeamountsoftriacylglycerolsareformedfromthehugeintakeofcarbohydra...