碳水化合物56-課件

MetabolismofCarbohydratesMetabolismofCarbohydrates1Conceptofcarbohydrate碳水化合物，其化學本質(zhì)為多羥醛或多羥酮類及其衍生物或多聚物。ClassesofcarbohydratemonosacchrideoligosacchridepolysacchrideglycoconjugateConceptofcarbohydrateClasse2glucose——已醛糖fructose——已酮糖MonosacchrideglucosefructoseMonosacchri3galactose——已醛糖

ribose——戊醛糖

galactoseribose4Oligosacchridemaltose:glucose—glucosesucrose:glucose—fructoselactose:glucose—galactose能水解生成幾分子單糖的糖，各單糖之間借脫水縮合的糖苷鍵相連。Oligosacchridemaltose:glucose5Polysacchride能水解生成多個分子單糖的糖。starchglycogencellulosePolysacchridestarchglycogencel6Starch:oneofthechiefformsinwhichplantsstorefood

淀粉顆粒Starch:oneofthechiefforms7

glycogen

:theformsofglucosestoredintheanimals

Non-reduced

Reduced

glycogen:theformsofgluc8cellulose：食物中含有，人體因無-糖苷酶而不能利用。有刺激腸蠕動等作用。β-1,4-糖苷鍵cellulose：食物中含有，人體因無-糖苷酶而不能利用9SectionIIntroductionSectionIIntroduction10Physiologicalfunctions1.Providetheenergy--majorfunction2.carbo-sourcesofothermaterialsinthebody:aminoacids,fats,cholesterol3.Componentsofcells：glycoprotein、proteoglycan、glycolipid,etc.,nucleotidesPhysiologicalfunctions1.Pro11DigestionandAbsorptionofcarbohydratesDigestionofCarbohydratesMonosaccharidesDonotneedhydrolysisbeforeabsorptionVerylittle(ifany)inmostfeedsDi-andpoly-saccharidesRelativelylargemoleculesMustbehydrolyzedpriortoabsorptionHydrolyzedtomonosaccharidesOnlymonosaccharidescanbeabsorbedDigestionandAbsorptionofca12starchMaltose+麥芽三糖（40%）（25%）Dextrin

+異麥芽糖（30%）（5%）glucoseSalivaryAmylaseα-葡萄糖苷酶α-臨界糊精酶Processofdigestion腸粘膜上皮細胞刷狀緣stomach

MouthSmallIntestinePancreaticAmylasestarchMaltose+麥芽三糖Dextrin+異13OverviewMonogastricCarbohydrateDigestionLocation

Enzymes

FormofDietaryCHOMouthSalivaryAmylase StarchMaltoseSucroseLactoseStomach(amylasefromsaliva)Dextrin→MaltoseSmallIntestinePancreaticAmylaseMaltose

BrushBorderEnzymesGlucoseFructoseGalactose+++GlucoseGlucoseGlucoseLargeIntestine None BacterialMicrofloraFermentCelluloseOverviewMonogastricCarbohydr14CarbohydrateAbsorptionlocation：duodenumandjejunumformation：monosacchridemechanism：activetransportNa+-dependentglucosetransporter,SGLTCarbohydrateAbsorptionlocatio15ADP+PiATPGNa+K+Na+pumpIntestinalepithelialcell

腸腔PortalVeinBrushBorder細胞內(nèi)膜ADP+PiATPGNa+K+Na16CarbohydratesMonosaccharidesSmallIntestineActiveTransportLiverPortalVeinDistributedtotissuethroughcirculationGLUT(glucosetransporter)GLUT1～5)Carbohydrates17Outlineofcarbohydrate

metabolism

Glucose酵解途徑

pyruvateAerobicanaerobicH2O及CO2

lactate糖異生途徑

lactate、aminoacid、glycerolglycogen肝糖原分解

糖原合成磷酸戊糖途徑

ribose+NADPH+H+starchDigestionandabsorptionATP

Outlineofcarbohydratemetabo18catabolicpathwayofcarbohydratesanaerobicglycolysisAerobicoxidationpentosepathwaycatabolicpathwayofanaerobi19SectionII

GlycolysisSectionII

Glycolysis20TheprocessofglycolysisStageI：glucosedigestedtopyruvate——Glycolysispathway

stageII：Theconversionofpyruvatetolactate*Definition：GlycolysisisthesequenceofreactionsthatconvertsglucoseintolactatewiththeconcomitantproductionofATP,underanaerobicconditions*twostagesofglycolysis*thereactionsite:cytosolTheprocessofglycolysisStage21⑴TheconversionofglucosetoGlucose-6-phosphateATPADPMg2+hexokinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate（一）TheconversionofonemoleculeofglucosetwomoleculesofpyruvateATPneededUnreversereactionGlucose-6-phosphateG-6-P⑴Theconversionofglucoseto22Fourtypesofhexokinaseinthemammals(typeⅠtoⅣ)TypeⅣlocatedinthelivercells：①appetencytoglucoseisverylow②regulatedbyhormonesFourtypesofhexokinaseinth23⑵Theconversionofglucose-6-phosphatetofructose-6-phosphatePhosphoglucoseisomeraseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateglucose-6-phosphate(G-6-P）fructose-6-phosphate(F-6-P）⑵Theconversionofglucose-6-24⑶TheconversionofF-6-Ptofructose-1,6-diphosphateATPADP

Mg2+

phosphofructokinase（FPK）GluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateATPneededunreverse

(F-6-P）fructose-1,6-Diphosphate(F-1,6-2-P)⑶TheconversionofF-6-Ptof25⑷TheconversionofF-1,6-2Pconvertedto2moleculesoftriosephosphate

aldolaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvatefructose-1,6-diphosphate(F-1,6-2P）DihydroxyacetonephosphateGlyceraldehyde3-phosphate⑷TheconversionofF-1,6-2Pc26⑸Theisomerizationof

triosephosphateTriosephosphateisomeraseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvatedihydroxyacetonephosphateglyceraldehyde3-phosphate⑸Theisomerizationoftrios27Onemoleculeofglucoseisconvertedtotwomoleculesofglyceraldehyde3-phosphate，whichconsumestwoATPThefollowingstepscanberegardedasthereactionoftwoglyceraldehyde3-phosphateOnemoleculeofglucoseiscon28⑹oxygenationofglyceraldehyde3-phosphateto1,3-diphospho-glyceratePi、NAD+NADH+H+

Glyceraldehyde3phosphatedehydrogenaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateTheonlydehydrogenationreactioninGlycolysis1,3-BPGishigh-energycompoundPO32-Glyceraldehyde3-phosphate1,3-diphospho-glycerate(1,3-BPG)⑹oxygenationofglyceraldehyd29⑺Theconversionofdiphosphoglycerateto3-phosphoglycerateADPATP

PhosphoglyceratekinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate

1stsubstrate-levelphosphorylationOPO32-diphosphoglycerate(1,3-BPG)3-phosphoglycerate⑺Theconversionofdiphosphog30⑻Theconversionof3-phospho-glycerateto2-phosphoglyceratePhosphoglyceratemutaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate3-phospho-glycerate2-phosphoglycerate⑻Theconversionof3-phospho-31⑼Theconversionof2-phosphoglyceratetophosphoenolpyruvateenolase(Mg2+/Mn2+)GluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvatePEPisahighenergycompound2-phosphoglycerate

phosphoenolpyruvateH2O⑼Theconversionof2-phosphog32ADPATP

K+Mg2+PyruvatekinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate⑽TheconversionofPhosphoenolpyruvatetopyruvate2ndsubstrate-levelphosphorylation

PhosphoenolpyruvateenolpyruvatepyruvateADPATPK+Mg2+Pyruvatekin33

(二)Theconversionoftwomoleculesofpyruvatetotwomoleculesoflactate

pyruvatelactateNADH+H+

maycomefromdehydrogenationofGlyceraldehyde3-phosphateLactatedehydrogenase(LDH)

NADH+H+

NAD+(二)Theconversionoftwomol34E1:hexokinase

E2:phosphofructokinaseE3:PyruvatekinaseNAD+lactateGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphosphoglycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetonephosphateGlyceraldehyde3-phosphateNAD+NADH+H+ADPATPADPATPphosphoenolpyruvateE2E1E3NADH+H+E1:hexokinaseE2:phosphofruc35Summaryofglycolysis

⑴reactionsite：cytosol⑵Glycolysisisananaerobicprocess⑶includingthreeunreversereactionsGG-6-PATP

ADPhexokinaseATP

ADPF-6-PF-1,6-2PphosphofructokinaseADPATP

PEPpyruvatePyruvatekinaseSummaryofglycolysis⑴react36⑷Theformandnumbersofenergyproductionform：substrate-levelphosphorylationPurenumbersofATP：Onemoleculeofglucose2×2-2=2ATPOneglucoseunitfromglycogen2×2-1=3ATP⑸fatesoflactateUsedbydegradationLactatecycle（gluconeogenesis

）⑷Theformandnumbersofener37fructosehexokinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADPpyruvategalactoseGalactose-1-PGlucose-1-PkinaseisomeraseMannose

Mannose-6-PhexokinaseisomeraseOtherhexosescanenterintoglycolysisfructosehexokinaseGluG-6-PF-6-38二、regulationofglycolysisKeyenzymes①hexokinase

②phosphofructokinase③

PyruvatekinaseForms①allostericregulation②covalentmodification二、regulationofglycolysisKey39（一）6-phosphofructokinase

-1(PFK-1)*allostericregulationallostericactivator：F-2,6-2P;

AMP;ADP;F-1,6-2P;

allostericinhibitor：citricacid;ATP

F-1,6-2PactivatedbypositivefeedbackAMP、ATPcompetetheallostericsiteoutsideoftheactivationcenter（一）6-phosphofructokinase-140F-6-PF-1,6-2PATPADPPFK-1PP2BPiPKAATPADPPiGlucagonATPcAMP

activationF-2,6-2P+++–/+AMP+citricacid–AMP+citricacid–PFK-2（withactivation）FBP-2（withoutactivation）6-PFK-2

PFK-2（withoutactivation）FBP-2（withactivation）PPFructoseBisphosphatase-2

F-6-PF-1,6-2PATPADPPFK-41（二）Pyruvatekinase1.allostericregulationallostericinhibitor：ATP,Alanine

allostericactivator：fructose-1,6-diphosphate（二）Pyruvatekinase1.alloster422.RegulationofcovalentmodificationPyruvatekinasePyruvatekinaseATPADPPiphosphoproteinphosphatase（withoutactivaiton）

（withactivation）

GlucagonPKA,CaMkinasePPKA：proteinkinaseACaM：Calmodulin2.Regulationofcovalentmodi43

(三)hexokinaseorglucosekinase*Glucose-6-phosphatehasfeedbackinhibitiononhexokiase，buthasnoeffectonglucosekinaseinliver*Long-chainacyl-CoAestershasallostericinhibitiononglucosekinaseinliver(三)hexokinaseorglucoseki44三、PhysiologicroleofglycolysisTheeffectivewayofenergyproductionunderanaerobicconditions2.Theimportantenergyproductionpathwayunderanaerobicconditionsinsomecells①Cellswithoutmitochondria：redbloodcells

②cellswithactivemetabolism：whitebloodcells,bonemarrowcells三、Physiologicroleofglycol45SectionIII

AerobicOxidationofCarbohydrateSectionIII

AerobicOxidatio46Reactionsite：cytosolandmitochondriaconcept:whenoxygenisenough，glucoseoxidationisprocessingcompletelytoproduceH2OandCO2，andtoreleaseenergy.Reactionsite：concept:47TheProcessofAerobicOxidationofCarbohydratesStage1：glycolysispathwayStage2：oxidativedecarxylationofpyruvateStage3：TACcycleG（Gn）

Stage4：oxidativephosphorylationpyruvateacetylCoA

CO2NADH+H+FADH2H2O[O]ATPADPTACcycle

cytosolmitochondriaTheProcessofAerobicOxidati48（一）oxidativedecarboxylationofpyruvatepyruvateacetylCoANAD+,HSCoACO2,NADH+H+

PyruvateDehydrogenasecomplex（一）oxidativedecarboxylationo49ComponentsofPyruvateDehydrogenasecomplex

enzymeE1：PyruvateDehydrogenase

E2：DehydrolipoylTransacetylaseE3：DehydrolipoylDehydrogenaseHSCoANAD+co-enzymeTPP

Lipoicacid（)HSCoAFAD,NAD+SSLComponentsofPyruvateDehydro50CO2CoASHNAD+NADH+H+5.

NADH+H+的生成1.-羥乙基-TPP的生成

2.乙酰硫辛酰胺的生成

3.乙酰CoA的生成4.硫辛酰胺的生成

CO2CoASHNAD+NADH+H+5.NADH+H51TAC、citricacidcycle、Krebscycle（二）TricarboxylicacidCycle,TAC*introductionReactionsite

mitochondriaTAC、citricacidcycle、Krebscy52CoASHNADH+H+NAD+CO2NAD+NADH+H+CO2GTPGDP+PiFADFADH2NADH+H+NAD+H2OH2OH2OCoASHCoASH⑧①②③④⑤⑥⑦②H2O①Citratesynthase②aconitase③Isocitratedehydrogenase

④α-ketoglutaratedehydrogenasecomplex⑤succinyl-CoAsynthetase⑥Succinatedehydrogenase⑦fumurase⑧MalatedehydrogenaseGTPGDPATPADPAMPkinaseCoASHNADH+H+NAD+CO2NAD+NADH+H+53⑴Synthesisofcitrate：un-reversereactionO=C-COOHCH3CH2COOHCH2+C=OHO-C-COO-COOHSCoACH2COOHOxaloacetateacetylCoAcitrateCitratesynthaseH2OCoA-SHUn-reversereaction⑴Synthesisofcitrate：un-rev54⑵synthesisofisocitrateCOO-COO-COO-CH2CHH-C-OH-OOC-C-OH

-OOC-C-OOC-C-H

CH2

CH2CH2COO-COO-COO-Citratecis-AconitateisocitrateH2OH2O⑵synthesisofisocitrateH2OH55⑶1stoxidativedecarboxylationtoformα-ketoglutarate：COO-COO-

H-C-OHC=O

-OOC-C-HCH2

CH2CH2COO-COO-

isocitrateα-ketoglutarateIsocitratedehydrogenase

NAD+NADH+H+CO2Mg2+Un-reversereaction⑶1stoxidativedecarboxylatio56⑷1stoxidativedecarboxylationtoformsuccinyl-CoA:COO-

O=C～SCoA

C=OCH2CH2CH2CH2COO-COO-α-ketoglutaratesuccinyl-CoA

highenergycompoundα-ketoglutaratedehydrogenasecomplexNAD+CoA-SHNADH+H+CO2Un-reversereaction⑷1stoxidativedecarboxylatio57⑸substrate-levelphosphorylation：catalysedbysuccinyl-CoAsynthetaseO=C～SCoACOO-CH2CH2CH2CH2COO-COO-succinyl-CoAsuccinateTheonlysubstrate-levelphosphorylationinTACtoproduceGTPsuccinyl-CoAsynthetaseGDP+PiGTP+CoA⑸substrate-levelphosphorylati58⑹dehydrogenationofsuccinatetoformfumarate:CH2-COO-HC-COO-CH2-COO--OOC-C-HSuccinatefumarateSuccinatedehydrogenaseFADFADH2⑹dehydrogenationofsuccinate59⑺Formationofmalate：HC-COO-

HO-CH-COO--OOC-C-HCH2-COO-fumaratemalate

fumuraseH2O⑺Formationofmalate：fumurase60⑻FormationofOxaloacetate：HO-CH-COO-

O=C-COOHCH2-COO-CH2-COO-MalateOxaloacetateMalatedehydrogenaseNAD+NADH+H+

⑻FormationofOxaloacetate：M61SummaryofTAC

①ConceptofTAC：Acetyl-CoA+Oxaloacetatecitrate→repeatdehydrogenationanddecarboxylation→Oxaloacetate.Acetyl-CoAisoxidated.②thereactionislocatedinmitochondriaSummaryofTAC①Conceptof62③PointsofTACcycleFourtimesofdehydrogenation，threeun-reversereaction,twotimesofdecarboxylation，onetimeofsubstrate-levelphosphorylationAfterTACcycle,onemolecularofacetyl-CoAforms：1FADH2，3NADH+H+，2CO2，1GTP.Total:12ATP。Keyenzymes：Citratesynthase

α-ketoglutaratedehydrogenasecomplexIsocitratedehydrogenase③PointsofTACcycle63④thereactioncyclecannotbereversed⑤TCACycleIntermediatesactascatalyzerwithoutchangeofamountOxaloacetateandotherTACcycleIntermediatescannotbesynthesizeddirectlyfromacetyl-CoAIntermediatescannotbedirectlyoxidatedinTACcycletoformCO2andH2O④thereactioncyclecannotb64⑥RoleofTCACycleIntermediates：SomeoftheCycleIntermediatescanbeconvertedtoothermaterials,forexample：Oxaloacetateaspartateα-ketoglutarateGlutaminecitrateFattyacid

SuccinylCoA

porphyrin

⑥RoleofTCACycleIntermedia65Whensugarsupplyisnotenough，malate、oxaloacetate→pyruvate→acetyl-CoA→TAC，theabsenceofoxaloacetatecancourseTACobstacleoxaloacetateoxaloacetatedecarboxyase

PyruvateCO2

malate蘋果酸酶PyruvateCO2

NAD+

NADH

+H+

Whensugarsupplyisnotenoug66*Recruitofoxaloacetate

：

oxaloacetatecitrateCitratelyaseAcetyl-CoApyruvatePyruvatecarboxylase

CO2malateMalatedehydrogenaseNADH+H+NAD+aspartateglutamine－oxaloacetictransaminase

α-ketoglutarateglutamine*Recruitofoxaloacetate：ox672.PhysiologicalsignificanceofTACcycleThecommonpathwayofoxidativedegradationofthreemajornutrientsThehingelinkedthemetabolismofthreemajornutrientsProvidingsmallprecursormoleculesformetabolsimofothersubstancesProcvidingH++eforrespiratorychain2.Physiologicalsignificance68H++eenterintorespiratorychainwheretheycanbeoxidationcompletelytoproduceH2O,coupledwithoxidativephosphorylationtoformATPfromADPNADH+H+

H2O、3ATP

[O]H2O、2ATP

FADH2

[O]

二、AerobicOxidationtocreateATP

H++eenterintorespiratory691molglucoseStageI：2（3）×2+4-2=6（8）StageII：3×2=6StageIII：12×2=24Tptal=36（38）mol

1molglucose70ThephysiologicalsignificanceofAerobicOxidationThemostmajorpathwaytoprovideenergyinmosttissuesofthehumanbeingsThephysiologicalsignificance71三、regulationofAerobicOxidation①glycolysis：hexokinase②oxidativedecarboxylationofpyruvate：PyruvateDehydrogenasecomplex③TACcycle：citratesynthase

Pyruvatekinase6-phosphofructokinase-1α-ketoglutaratedehydrogenasecomplexIsocitratedehydrogenaseKeyenzymes三、regulationofAerobicOxidat721.PyruvateDehydrogenasecomplex⑴allostericregulationallostericinhibitor：Acetyl-CoA;NADH;ATPallostericactivator：AMP;ADP;NAD+*Acetyl-CoA/HSCoAorNADH/NAD+，inhibit1.PyruvateDehydrogenasecomp73⑵Regulationofcovalentmodification

目錄pyruvate⑵Regulationof目錄pyruvate74Acetyl-CoAcitrateoxaloacetateSuccinylCoAα-ketoglutarateisocitratemalateNADHFADH2GTPATPIsocitratedehydrogenaseCitratesynthaseα-ketoglutaratedehydrogenasecomplex–ATP

+ADP

ADP

+ATP

–citrateSuccinyl-CoANADH–Succinyl-CoA

NADH+Ca2+Ca2+①ATP、ADP②inhibitionbyproductionaccumulation③allostericfeedbackinhibitionbyIntermediates④others,esp:Ca2+canactivatemanyenzymes2.RegulationofTACcycleAcetyl-CoAcitrateoxaloacetat75CharacteristicsofregulationofAerobicOxidation⑴Regulationbykeyenzymes⑵RegulationbyATP/ADPorATP/AMPratiothroughthewholeprocess⑶TACcycleaffectedbythespeedofoxidativephosphorylation⑷harmonyregulationbetweenTACcycleandglycolysispathway.glycolysispathwaywhichprovidespyruvatetoformacetyl-CoAisdependentontheneedofTACcycle.Characteristicsofregulation762ADPATP+AMPAdenylateKinaseTheconcentrationofATPinthebodyis50-foldmorethanAMP.Aftertheabovereaction，thechangeofATP/AMPislargerthanthatofATP,whichleadstosignalamplificationRegulationbyATP/ADPorATP/AMPration，theinfluencebyATP/AMPismorenotable2ADPATP+AMPAdenylateKinas77四、Pastuereffect：*concept：thephenomenonofglycolysisinhibitionbyAerobicOxidation*mechanism

Inthepresenceofoxygen，NADH+H+eenterintothemitochondriatobeoxidationandtheconversionofpyruvatetolactateissuppressed.IntheAbsenceofoxygen，glycolysispathwayisenhanced，theconcentrationofNADH+H+incytosolincreasesandpyruvateisconvertedtolactateashydrogenacceptor四、Pastuereffect：*concept：the78SectionVI

PentosePhosphatePathwaySectionVI

PentosePhosphate79*concept：磷酸戊糖途徑是指由葡萄糖生成磷酸戊糖及NADPH+H+，前者再進一步轉(zhuǎn)變成3-磷酸甘油醛和6-磷酸果糖的反應過程。*concept：磷酸戊糖途徑是指由葡萄糖生成磷酸戊糖及N80*Site：cytosolStageI：oxidativereactionToform

PentosePhosphate，NADPH+H+andCO2一、theprocessofPentosePhosphatepathway*Thereactionincludestwostages

StageII：grouptransferreaction*Site：cytosolStageI：oxidati816-磷酸葡萄糖酸5-磷酸核酮糖

NADPH+H+NADP+⑴H2ONADP+

CO2

NADPH+H+⑵6-磷酸葡萄糖脫氫酶6-磷酸葡萄糖酸脫氫酶

HCOHCH2OHCOGlucose-6-phosphate6-磷酸葡萄糖酸內(nèi)酯1.TheformationofPentosePhosphate

5-磷酸核糖

6-磷酸葡萄糖酸5-磷酸核酮糖NADPH+826-磷酸葡萄糖脫氫酶是關(guān)鍵酶。兩次脫氫生成NADPH+H+。磷酸核糖是非常重要的中間產(chǎn)物。G-6-P5-磷酸核糖NADP+

NADPH+H+

NADP+

NADPH+H+

CO2

6-磷酸葡萄糖脫氫酶是關(guān)鍵酶。G-6-P5-磷酸核糖83磷酸戊糖通過3C、4C、6C、7C等演變，最終生成3-磷酸甘油醛和6-磷酸果糖。3-磷酸甘油醛和6-磷酸果糖，可進入酵解途徑。2.基團轉(zhuǎn)移反應磷酸戊糖通過3C、4C、6C、7C等演變，最終生成3-磷酸甘845-磷酸核酮糖(C5)×35-磷酸核糖C55-磷酸木酮糖

C55-磷酸木酮糖

C57-磷酸景天糖C73-磷酸甘油醛

C34-磷酸赤蘚糖

C46-磷酸果糖

C66-磷酸果糖

C63-磷酸甘油醛

C35-磷酸核酮糖(C5)×35-磷酸核糖5-磷酸木85磷酸戊糖途徑第一階段

第二階段

5-磷酸木酮糖C55-磷酸木酮糖C57-磷酸景天糖C73-磷酸甘油醛C34-磷酸赤蘚糖C46-磷酸果糖C66-磷酸果糖C63-磷酸甘油醛

C36-磷酸葡萄糖(C6)×36-磷酸葡萄糖酸內(nèi)酯(C6)×36-磷酸葡萄糖酸(C6)×35-磷酸核酮糖(C5)×35-磷酸核糖C53NADP+3NADP+3H+6-磷酸葡萄糖脫氫酶

3NADP+3NADP+3H+6-磷酸葡萄糖酸脫氫酶CO2磷酸戊糖途徑第一階段第二階段5-磷酸木酮糖5-磷86總反應式：3×6-磷酸葡萄糖+6NADP+

2×6-磷酸果糖+3-磷酸甘油醛+6NADPH+H++3CO2總反應式：3×6-磷酸葡萄糖+6NADP+87磷酸戊糖途徑的特點

生成NADPH+H+生成5-磷酸核糖3、4、5、6、7碳糖的演變磷酸戊糖途徑的特點生成NADPH+H+88二、磷酸戊糖途徑的調(diào)節(jié)*6-磷酸葡萄糖脫氫酶是關(guān)鍵酶*NADPH/NADP+比值升高抑制，降低激活。二、磷酸戊糖途徑的調(diào)節(jié)*6-磷酸葡萄糖脫氫酶是關(guān)鍵酶89三、磷酸戊糖途徑的生理意義（一）為核苷酸的生成提供核糖（二）提供NADPH作為供氫體參與多種代謝反應三、磷酸戊糖途徑的生理意義（一）為核苷酸的生成提供核糖901.NADPH是體內(nèi)許多合成代謝的供氫體2.NADPH參與體內(nèi)的羥化反應，與生物合成或生物轉(zhuǎn)化有關(guān)3.NADPH可維持GSH的還原性2G-SHG-S-S-GNADP+NADPH+H+AAH21.NADPH是體內(nèi)許多合成代謝的供氫體2.NA91SectionV

GlycogenesisandGlycogenolysisSectionV

Glycogenesisand92糖原儲存的主要器官及其生理意義肌糖原，180∽300g，為肌肉收縮氧化供能肝糖原，70∽100g，維持血糖水平

糖原儲存的主要器官及其生理意義931.葡萄糖單元以α-1,4-糖苷鍵形成長鏈。2.約10個葡萄糖單元處形成分枝，分枝處葡萄糖以α-1,6-糖苷鍵連接，分支增加，溶解度增加。3.每條鏈都終止于一個非還原端.非還原端增多，以利于其被酶分解。糖原的結(jié)構(gòu)特點及其意義目錄1.葡萄糖單元以α-1,4-糖苷鍵形成長鏈。糖原的結(jié)構(gòu)特94一、糖原的合成代謝（二）合成部位（一）定義糖原的合成(glycogenesis)指由葡萄糖合成糖原的過程。肝、肌肉細胞胞漿一、糖原的合成代謝（二）合成部位（一）定義糖原的合成(gl95葡萄糖6-磷酸葡萄糖1-磷酸葡萄糖變位酶UDPGUDPG焦磷酸化酶UTPPPiOCH2OHpp尿苷糖原n糖原n+1+UDP

糖原合酶（三）糖原合成途徑葡萄糖6-磷酸葡萄糖1-磷酸葡萄糖變位酶UDPGUDPG焦磷961.葡萄糖磷酸化生成6-磷酸葡萄糖葡萄糖6-磷酸葡萄糖

ATP

ADP

己糖激酶;葡萄糖激酶（肝）1.葡萄糖磷酸化生成6-磷酸葡萄糖葡萄糖6-磷酸葡971-磷酸葡萄糖

磷酸葡萄糖變位酶6-磷酸葡萄糖

2.6-磷酸葡萄糖轉(zhuǎn)變成1-磷酸葡萄糖1-磷酸葡萄糖磷酸葡萄糖變位酶6-磷酸葡萄糖98+UTP尿苷

PPPPPiUDPG焦磷酸化酶

3.1-磷酸葡萄糖轉(zhuǎn)變成尿苷二磷酸葡萄糖1-磷酸葡萄糖

尿苷二磷酸葡萄糖

UDPG+UTP尿苷PPPPPiUDPG焦磷酸化酶99糖原n+UDPG糖原n+1+UDP

糖原合酶UDPUTPADPATP核苷二磷酸激酶4.α-1,4-糖苷鍵式結(jié)合——糖鏈延長糖原n：較小糖原分子，糖原引物，UDPG上葡萄糖基的接受體。糖原n+UDPG糖原n+1+UDP100糖原合酶催化糖原糖鏈末端延長：糖原合酶pp尿苷pp尿苷糖原（n）糖原（n+1）反應反復進行，糖鏈不斷延長。糖原合酶催化糖原糖鏈末端延長：糖原合酶pp尿苷pp尿苷糖原（1015.糖原分枝的形成

分支酶

α-1,6-糖苷鍵α-1,4-糖苷鍵

當糖鏈長度達到12～18個葡萄糖基時轉(zhuǎn)移6～7個葡萄糖基5.糖原分枝的形成分支酶102近來人們在糖原分子的核心發(fā)現(xiàn)了一種名為glycogenin的蛋白質(zhì)。Glycogenin可對其自身進行共價修飾，將UDP-葡萄糖分子的C1結(jié)合到其酶分子的酪氨酸殘基上，從而使它糖基化。這個結(jié)合上去的葡萄糖分子即成為糖原合成時的引物。作為引物的第一個糖原分子從何而來？近來人們在糖原分子的核心發(fā)現(xiàn)了一種名為glycogenin的103碳水化合物56-課件104二、糖原的分解代謝*定義*肝糖元的分解糖原分解(glycogenolysis)習慣上指肝糖原分解成為葡萄糖的過程。二、糖原的分解代謝*定義*肝糖元的分解糖原分解105糖原（n）糖原（n-1）磷酸1-磷酸葡萄糖6-磷酸葡萄糖葡萄糖H2OPi葡萄糖6-磷酸酶（肝、腎）糖原磷酸化酶6-磷酸果糖糖酵解途徑（肌肉）1.糖原的磷酸解糖原（n）糖原（n-1）磷酸1-磷酸葡萄糖6-磷酸葡萄糖葡萄106脫枝酶

(debranchingenzyme)2.

脫枝酶的作用

①轉(zhuǎn)移葡萄糖殘基②水解-1,6-糖苷鍵磷酸化酶轉(zhuǎn)移酶活性α-1,6糖苷酶活性目錄脫枝酶(debranchingenzyme)2.107*肌糖原的分解Glu→G-6-P同肝糖原分解肌肉組織中無葡萄糖-6-磷酸酶，所以6-磷酸葡萄糖不能轉(zhuǎn)變成葡萄糖補充血糖，只能進入酵解途徑代謝。肌糖原的分解與合成與乳酸循環(huán)有關(guān)。*肌糖原的分解Glu→G-6-P同肝糖原分解108糖原的合成與分解小結(jié)UDPG焦磷酸化酶