糖代謝-jiang

1、Metabolism of CarbohydratesConcept of carbohydrate 碳水化合物，其化學(xué)本質(zhì)為多羥醛或多羥碳水化合物，其化學(xué)本質(zhì)為多羥醛或多羥酮類及其衍生物或多聚物。酮類及其衍生物或多聚物。Classes of carbohydrate monosacchride oligosacchridepolysacchrideglycoconjugateOHOHHHOHHOHOOHOOHHHHOHOHHOHHCH2OH glucose 已醛糖已醛糖 fructose 已酮糖已酮糖 OHOHOHOHHHOHHOHMonosacchrideOOHOHHOH2CHHOHHCH

2、2OHOOHHHOHHOHHOHHCH2OHOHHHHOHOHOHHOH2COHOHOHOHHOHHHOH galactose 已醛糖已醛糖 ribose 戊醛糖戊醛糖 OHHOHHOHOHOHOligosacchridemaltose: glucoseglucose sucrose: glucosefructoselactose: glucosegalactose能水解生成幾分子單糖的糖，各單糖之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。間借脫水縮合的糖苷鍵相連。Polysacchride能水解生成多個分子單糖的糖。能水解生成多個分子單糖的糖。starchglycogenc

3、elluloseStarch: one of the chief forms in which plants store food 淀粉淀粉顆粒顆粒 glycogen : the forms of glucose stored in the animals Non-reduced Reduced cellulose：食物中含有，人體因無食物中含有，人體因無 -糖苷酶而不能利糖苷酶而不能利用。有刺激腸蠕動等作用。用。有刺激腸蠕動等作用。-1,4-糖苷鍵糖苷鍵Section I1. Provide the energy-major function2. carbo-sources of other

4、 materials in the body: amino acids, fats, cholesterol 3. Components of cells：glycoprotein、proteoglycan 、glycolipid, etc., nucleotides Digestion and Absorption of carbohydratesDigestion of CarbohydratesMonosaccharidesDo not need hydrolysis before absorptionVery little (if any) in most feedsDi- and p

5、oly-saccharidesRelatively large moleculesMust be hydrolyzed prior to absorptionHydrolyzed to monosaccharidesOnly monosaccharides can be absorbedstarchMaltose +麥芽三糖麥芽三糖 （40%） （25%）Dextrin +異麥芽糖異麥芽糖 （30%） （5%）glucoseSalivary Amylase- -葡萄糖苷酶葡萄糖苷酶- -臨界糊精酶臨界糊精酶 Process of digestion 腸粘膜腸粘膜上皮細(xì)上皮細(xì)胞刷狀胞刷狀緣緣 s

6、tomach MouthMouthSmall IntestinePancreatic AmylaseOverview Monogastric Carbohydrate DigestionLocation Enzymes Form of Dietary CHOMouth Salivary Amylase Starch Maltose Sucrose LactoseStomach (amylase from saliva) DextrinMaltoseSmall Intestine Pancreatic Amylase Maltose Brush Border Enzymes Glucose Fr

7、uctose Galactose + + + Glucose Glucose GlucoseLarge Intestine NoneBacterial Microflora Ferment Cellulose Carbohydrate Absorption location： duodenum and jejunum formation： monosacchride mechanism：active transportNa+-dependent glucose transporter, SGLTADP+Pi ATP G Na+ K+ Na+pumpIntestinal epithelial c

8、ell 腸腸腔腔 Portal VeinBrush Border細(xì)胞內(nèi)膜細(xì)胞內(nèi)膜 Carbohydrates MonosaccharidesSmall IntestineActive TransportLiverPortal VeinDistributed to tissue through circulationG L U T ( g l u c o s e transporter ) G L U T 15)Outline of carbohydrate metabolism Glucose酵解途徑 pyruvateAerobicanaerobicH2O及CO2 lactate糖異生途徑 l

9、actate、amino acid、glycerol glycogen肝糖原分解 糖原合成磷酸戊糖途徑 ribose + NADPH+HNADPH+H+ +starchDigestion and absorption ATPATP catabolic pathway of carbohydratesanaerobic glycolysisAerobicoxidationpentose pathwaySection IIGlycolysisThe process of glycolysis Stage I ：glucose digested to pyruvate Glycolysis path

10、way stageII：The conversion of pyruvate to lactate* *Definition： Glycolysis is the sequence of reactions that converts glucose into lactate with the concomitant production of ATP,under anaerobic conditions* *two stages of glycolysis * *the reaction site: cytosol The conversion of glucose to Glucose-6

11、-phosphateATP ADPMg2+ hexokinaseGlu G-6-P F-6-P F-1,6-2PATP ADP ATP ADP 1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate（一）（一）The conversion of one molecule of glucose two molecules of p

12、yruvateATP neededUnreverse reaction HCCCCCCH2OHOHOHOHHHOHHOHPO3H2CHOCCCCCH2HOHHOHOHHHOHOGlucose-6-phosphate G-6-PFour types of hexokinase in the mammals (typeto )Type located in the liver cells：appetency to glucose is very lowregulated by hormones The conversion of glucose-6-phosphate to fructose-6-

13、phosphatePhosphoglucoseisomeraseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateglucose-6-phosphate(G-6-P）HCCCCCCH2OOHOHOHHHOHHOHPOOHOHfructose-6-phospha

14、te(F-6-P）OHCH2CCCCCH2OOOHHHOHHOHP OOHOH The conversion of F-6-P to fructose-1,6-diphosphate ATP ADP Mg2+ phosphofructokinase （FPK）GluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATP

15、ADPATPPhosphoenolpyruvateATP neededunreverse (F-6-P）OHCH2CCCCCH2OOOHHHOHHOHPOOHOHfructose-1,6-Diphosphate(F-1,6-2-P)O-CH2CCCCCH2OOOHHHOHHOHP OOHOHO-P OOHOH The conversion of F-1,6-2P converted to 2 molecules of triose phosphate aldolaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phosph

16、o-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvatefructose-1,6-diphosphate(F-1,6-2P）CCCCCH2OOOHHHOHHOHCH2OPOOHOHPOOHOHDihydroxyacetone phosphateOHCH2COCH2OPOOHOHGlyceraldehyde 3-phosphateOHHOCCHCH2OPOOHOH The isomerizat

17、ion of triose phosphateTriose phosphate isomeraseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateO HCH2COCH2O P OOHOHOHHOCCHCH2OPOOHOHdihydroxyacetone ph

18、osphateglyceraldehyde 3-phosphate One molecule of glucose is converted to two molecules of glyceraldehyde 3-phosphate ，which consumes two ATP The following steps can be regarded as the reaction of two glyceraldehyde 3-phosphate oxygenation of glyceraldehyde 3-phosphate to 1,3-diphospho-glyceratePi、N

19、AD+ NADH+H+ Glyceraldehyde3 phosphate dehydrogenaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateThe only dehydrogenation reaction in Glycolysis1,3-BPG

20、 is high-energy compoundOHHOCCHCH2OPOOHOHOHO-OCCHCH2OPOOHOH PO32-Glyceraldehyde 3-phosphate1,3-diphospho-glycerate(1,3-BPG)diphosphoglycerate to 3-phosphoglycerateADP ATP Phosphoglycerate kinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihyd

21、roxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate 1st substrate-level phosphorylationHOHOOCCHCH2OPOOHOHOHO-OCCHCH2OPOOHOHOPO32-diphosphoglycerate(1,3-BPG)3-phosphoglycerate The conversion of 3-phospho-glycerate to 2-phosphoglyceratePhosphoglycerate mutaseGluG-

22、6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvateHOHOOCCHCH2OPOOHOHOHHO-OOCCHCH2O-POOHOH3-phospho-glycerate2-phosphoglycerate The conversion of 2-phosphoglycer

23、ate to phosphoenolpyruvateenolase(Mg2+/Mn2+ )GluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvatePEP is a high energy compoundHOHHOOOCCCH2POOHOHO-HOOCCCH2P+O

24、OHOH2-phosphoglycerate phosphoenolpyruvateH2OADP ATP K+ Mg2+Pyruvate kinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADP1,3-diphospho-glycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+NADH+H+ADPATPADPATPPhosphoenolpyruvate The conversion of Phosphoenol

25、pyruvate to pyruvate2nd substrate-level phosphorylation PhosphoenolpyruvateO-HOOCCC H2P+OO HO HenolpyruvateCOO HO HC H2CCH3OCCOOHpyruvate (二二) The conversion of two molecules of pyruvate to two molecules of lactate pyruvatelactateNADH+H+ may come from dehydrogenation of Glyceraldehyde 3-phosphateLac

26、tate dehydrogenase (LDH) NADH + H+ NAD+ COOHCHOHCH3COOHC=OCH3E1: hexokinase E2: phosphofructokinaseE3: Pyruvate kinaseNAD+ lactateGluG-6-PF-6-PF-1, 6-2PATP ADP ATPADP1,3-diphosphoglycerate3-phospho-glycerate2-phosphoglyceratepyruvateDihydroxyacetone phosphateGlyceraldehyde 3-phosphateNAD+ NADH+H+ AD

27、P ATP ADP ATPphosphoenolpyruvateE2E1E3NADH+H+ Summary of glycolysis reaction site：cytosol Glycolysis is an anaerobic process including three unreverse reactions G G-6-P ATP ADP hexokinaseATP ADP F-6-P F-1,6-2P phosphofructokinaseADP ATP PEP pyruvatePyruvate kinase The form and numbers of energy prod

28、uction form：substrate-level phosphorylation Pure numbers of ATP：One molecule of glucose 22-2= 2ATPOne glucose unit from glycogen 22-1= 3ATP fates of lactate Used by degradationLactate cycle（gluconeogenesis ）fructosehexokinaseGluG-6-PF-6-PF-1,6-2PATPADPATPADPpyruvategalactoseGalactose-1-PGlucose-1-Pk

29、inaseisomeraseMannose Mannose -6-PhexokinaseisomeraseOther hexoses can enter into glycolysis二、二、regulation of glycolysisKey enzymes hexokinase phosphofructokinase Pyruvate kinaseForms allosteric regulation covalent modification （一）（一） 6- phosphofructokinase -1(PFK-1) * * allosteric regulation allost

30、eric activator ： F-2,6-2P; AMP; ADP; F-1,6-2P; allosteric inhibitor：citric acid ; ; ATPATP F-1,6-2P activated by positive feed back AMP、ATP compete the allosteric site outside of the activation centerF-6-P F-1,6-2P ATP ADP PFK-1PP2BPi PKA ATP ADP Pi GlucagonATP cAMP activationF-2,6-2P +/+AMP +citric

31、 acidAMP +citric acidPFK-2（with activation）FBP-2（without activation）6-PFK-2 PFK-2（ without activation ）FBP-2（ with activation ）PPFructose Bisphosphatase -2 （二）二） Pyruvate kinase1. allosteric regulation allosteric inhibitor：ATP, Alanine allosteric activator ： fructose-1,6-diphosphate2. Regulation of

32、covalent modification Pyruvate kinasePyruvate kinaseATP ATP ADP ADP Pi phosphoprotein phosphatase（without activaiton） （with activation） GlucagonPKA, CaM kinasePKA, CaM kinaseP PPKA：protein kinase ACaM：Calmodulin (三三) hexokinase or glucose kinase* Glucose-6-phosphate has feedback inhibition on hexoki

33、ase ，but has no effect on glucose kinase in liver* Long-chain acyl-CoA esters has allosteric inhibition on glucose kinase in liver 三、三、 Physiologic role of glycolysis1. The effective way of energy production under anaerobic conditions2. The important energy production pathway under anaerobic conditi

34、ons in some cells Cells without mitochondria：red blood cells cells with active metabolism ：white blood cells , bone marrow cellsSection III Aerobic Oxidation of CarbohydrateReaction site ： cytosol and mitochondriaconcept: when oxygen is enough，glucose oxidation is processing completely to produce H2

35、O and CO2，and to release energy.The Process of Aerobic Oxidation of CarbohydratesStage 1 ：glycolysis pathwayStage 2： oxidative decarxylation of pyruvateStage 3：TAC cycle G（Gn） Stage 4：oxidative phosphorylationpyruvateacetyl CoA CO2 NADH+H+ FADH2H2O O ATP ADP TAC cycle cytosolmitochondria（一）（一）oxidat

36、ive decarboxylation of pyruvatepyruvateacetyl CoA NAD+ , HSCoA CO2 , NADH + H+ Pyruvate Dehydrogenase complexComponents of Pyruvate Dehydrogenase complex enzymeE1： Pyruvate Dehydrogenase E2：Dehydrolipoyl Transacetylase E3：Dehydrolipoyl DehydrogenaseHSCoANAD+ co-enzyme TPP Lipoic acid（ ) HSCoA FAD, N

37、AD+SSLCO2 CoASHNAD+NADH+H+5. NADH+H+的生成的生成1. -羥乙基羥乙基-TPP的生成的生成 2.乙酰硫辛酰乙酰硫辛酰胺的生成胺的生成 3.乙酰乙酰CoA的生成的生成4. 硫辛酰胺的生成硫辛酰胺的生成 TAC、citric acid cycle、Krebs cycleTricarboxylic acid Cycle, TAC*introductionReaction site mitochondriaCoASHNADH+H+NAD+NAD+NADH+H+FADFADH2NADH+H+NAD+H2OH2OH2OCoASHCoASHH2O Citrate synth

38、aseaconitaseaconitase Isocitrate dehydrogenase -ketoglutaratedehydrogenase complexsuccinyl-CoA synthetasesuccinyl-CoA synthetase Succinate dehydrogenaseSuccinate dehydrogenasefumurasefumuraseMalate dehydrogenaseMalate dehydrogenaseGTPGDPATPADPAMP kinase Synthesis of citrate ：un-reverse reaction O=C-

39、COOH CH3 CH2COOH CH2 + C=O HO-C-COO- COOH SCoA CH2COOHOxaloacetate acetyl CoA citrateCitrate synthaseH2OCoA-SHUn-reverse reaction synthesis of isocitrate COO- COO- COO- CH2 CH H-C-OH- OOC-C-OH - OOC-C - OOC-C-H CH2 CH2 CH2 COO- COO- COO- Citrate cis-Aconitate isocitrate H2OH2O 1st oxidative decarbox

40、ylation to form-ketoglutarate： COO- COO- H-C-OH C=O -OOC-C-H CH2 CH2 CH2 COO- COO- isocitrate -ketoglutarateIsocitrate dehydrogenase NAD+NADH+H+CO2Mg2+Un-reverse reaction 1st oxidative decarboxylation to form succinyl-CoA: COO- O=CSCoA C=O CH2 CH2 CH2 CH2 COO- COO-ketoglutarate succinyl-CoA high ene

41、rgy compound-ketoglutarate dehydrogenase complexNAD+CoA-SHNADH+H+CO2Un-reverse reactionsubstrate-level phosphorylation：catalysed by succinyl-CoA synthetaseO=CSCoA COO- CH2 CH2 CH2 CH2 COO- COO-succinyl-CoA succinateThe only substrate-level phosphorylation in TAC to produce GTPsuccinyl-CoA synthetase

42、GDP+PiGTP+CoA dehydrogenation of succinate to form fumarate: CH2-COO- HC-COO- CH2-COO- -OOC-C-H Succinate fumarate Succinate dehydrogenaseFADFADH2 Formation of malate： HC-COO- HO-CH-COO- -OOC-C-H CH2-COO- fumarate malate fumuraseH2O Formation of Oxaloacetate： HO-CH-COO- O=C-COOH CH2-COO- CH2-COO- Ma

43、late Oxaloacetate MalatedehydrogenaseNAD+NADH+H+ Summary of TAC Concept of TAC：Acetyl-CoA+Oxaloacetatecitrate repeat dehydrogenation and decarboxylation Oxaloacetate. Acetyl-CoA is oxidated.the reaction is located in mitochondria Points of TAC cycle Four times of dehydrogenation ，three un-reverse re

44、action, two times of decarboxylation ，one time of substrate-level phosphorylation After TAC cycle, one molecular of acetyl-CoA forms：1 FADH2，3 NADH+H+，2 CO2， 1 GTP. Total: 12ATP 。 Key enzymes： Citrate synthase -ketoglutaratedehydrogenase complex Isocitrate dehydrogenase the reaction cycle can not be

45、 reversed TCA Cycle Intermediates act as catalyzer without change of amount Oxaloacetate and other TAC cycle Intermediates can not be synthesized directly from acetyl-CoA Intermediates can not be directly oxidated in TAC cycle to form CO2 and H2O Role of TCA Cycle Intermediates ： Some of the Cycle I

46、ntermediates can be converted to other materials, for example：Oxaloacetateaspartate e-ketoglutarateGlutaminecitrateFatty acid Succinyl CoA porphyrin When sugar supply is not enough，malate、oxaloacetatepyruvateacetyl-CoA TAC，the absence of oxaloacetateTAC obstacle oxaloacetateoxaloacetate decarboxyase

47、 Pyruvate CO2 malate蘋果酸酶蘋果酸酶 Pyruvate CO2 NAD+ NADH + H+ oxaloacetate oxaloacetatecitratecitrateCitratelyaseAcetyl-CoA pyruvatepyruvatePyruvatecarboxylase CO2 malatemalateMalatedehydrogenaseNADH+H+ NAD+ aspartateglutamineoxaloacetic transaminase -ketoglutarateglutamineglutamine The common pathway of

48、 oxidative degradation of three major nutrients The hinge linked the metabolism of three major nutrients Providing small precursor molecules for metabolsim of other substances Procviding H+ + e for respiratory chainH+ + e enter into respiratory chain where they can be oxidation completely to produce

49、 H2O, coupled with oxidative phosphorylation to form ATP from ADPNADH+H+ H2O、3ATP O H2O、2ATP FADH2 O 二、二、 Aerobic Oxidation to create ATP 1mol glucoseStage I： 2（3）2+4-2=6（8）Stage II： 3 2=6Stage III：122=24Tptal =36（38） mol The physiological significance of Aerobic Oxidation The most major pathway to

50、provide energy in most tissues of the human beings三、三、regulation of Aerobic Oxidation glycolysis glycolysis： hexokinase oxidative decarboxylation of pyruvate ：Pyruvate Dehydrogenase complex TAC cycle：citrate synthase Pyruvate kinase 6- phosphofructokinase -1-ketoglutarate dehydrogenase complexIsocit

51、rate dehydrogenaseKey enzymes1. Pyruvate Dehydrogenase complex allosteric regulationallosteric inhibitor ：Acetyl-CoA; NADH; ATP allosteric activator ：AMP; ADP; NAD+ * Acetyl-CoA/HSCoA or NADH/NAD+ ，inhibit Regulation of covalent modification 目目 錄錄pyruvateAcetyl-Acetyl-CoA citrateoxaloacetateSuccinyl

52、 CoA -ketoglutarateisocitratemalatemalate NADH FADH2 GTP ATP Isocitrate dehydrogenaseCitrate synthase-ketoglutarate dehydrogenase complexATP +ADP ADP +ATP citrateSuccinyl-CoA NADH Succinyl-CoA NADH +Ca2+ Ca2+ ATP、ADP inhibition by production accumulation allosteric f e e d b a c k inhibition by Inte

53、rmediates others, esp:Ca2+ can activate many enzymes2. Regulation of TAC cycleCharacteristics of regulation of Aerobic Oxidation Regulation by key enzymes Regulation by ATP/ADP or ATP/AMP ratio through the whole process TAC cycle affected by the speed of oxidative phosphorylation harmony regulation

54、between TAC cycle and glycolysis pathway . glycolysis pathway which provides pyruvate to form acetyl-CoA is dependent on the need of TAC cycle.2ADP ATP+AMP Adenylate Kinase The concentration of ATP in the body is 50-fold more than AMP. After the above reaction，the change of ATP/AMP is larger than th

55、at of ATP, which leads to signal amplification Regulation by ATP/ADP or ATP/AMP ration， the influence by ATP/AMP is more notable四、四、Pastuer effect：* concept：the phenomenon of glycolysis inhibition by Aerobic Oxidation* mechanism In the presence of oxygen，NADH+H+e enter into the mitochondria to be ox

56、idation and the conversion of pyruvate to lactate is suppressed.In the Absence of oxygen，glycolysis pathway is enhanced，the concentration of NADH+H+ in cytosol increases and pyruvate is converted to lactate as hydrogen acceptorSection VIPentose Phosphate Pathway* concept：磷酸戊糖途徑磷酸戊糖途徑是指由葡萄糖生是指由葡萄糖生成磷

57、酸戊糖及成磷酸戊糖及NADPH+HNADPH+H+ +，前者再，前者再進(jìn)一步轉(zhuǎn)變成進(jìn)一步轉(zhuǎn)變成3-3-磷酸甘油醛和磷酸甘油醛和6-6-磷酸果糖的反應(yīng)過程。磷酸果糖的反應(yīng)過程。* Site ：cytosolStage I：oxidative reaction To form Pentose Phosphate ， NADPH+H+ and CO2一、一、the process of Pentose Phosphate pathway* The reaction includes two stages Stage II Stage II：group transfer reactiongroup t

58、ransfer reactionCCCCCOOCH2OHOHOHOHHHHOHP P6-磷酸葡萄糖酸磷酸葡萄糖酸 CH2OHC=OCCCH2OOHOHHHP P5-磷酸核酮糖磷酸核酮糖 NADPH+H+ NADP+ H2O NADP+ CO2 NADPH+H+ 6-磷酸葡萄糖脫氫酶磷酸葡萄糖脫氫酶6-磷酸葡萄糖酸脫氫酶磷酸葡萄糖酸脫氫酶 CH2OH C O Glucose-6-phosphateCCCCCCH2OHOHOHOHHHHOHHOP P6-磷酸葡萄糖酸內(nèi)酯磷酸葡萄糖酸內(nèi)酯 CCCCC=OCH2OHOHOHHHHOHOP P1. The formation of Pentose Pho

59、sphate 5-磷酸核糖磷酸核糖 6-磷酸葡萄糖脫氫酶磷酸葡萄糖脫氫酶是關(guān)鍵酶。是關(guān)鍵酶。 兩次脫氫生成兩次脫氫生成NADPH + H+。 磷酸核糖是非常重要的中間產(chǎn)物。磷酸核糖是非常重要的中間產(chǎn)物。G-6-P 5-磷酸核糖磷酸核糖 NADP+ NADPH+H+ NADP+ NADPH+H+ CO2 磷酸戊糖磷酸戊糖通過通過3C3C、4C4C、6C6C、7C7C等演變，最等演變，最終生成終生成3- 3-磷酸甘油醛磷酸甘油醛和和6- 6-磷酸果糖磷酸果糖。 3- 3-磷酸甘油醛磷酸甘油醛和和6- 6-磷酸果糖磷酸果糖，可進(jìn)入酵解途，可進(jìn)入酵解途徑。徑。2. 基團(tuán)轉(zhuǎn)移反應(yīng)基團(tuán)轉(zhuǎn)移反應(yīng) 5-磷酸核

60、酮糖磷酸核酮糖(C5) 3 5-磷酸核糖磷酸核糖 C55-磷酸木酮糖磷酸木酮糖 C55-磷酸木酮糖磷酸木酮糖 C57-磷酸景天糖磷酸景天糖 C73-磷酸甘油醛磷酸甘油醛 C34-磷酸赤蘚糖磷酸赤蘚糖 C46-磷酸果糖磷酸果糖 C66-磷酸果糖磷酸果糖 C63-磷酸磷酸甘油醛甘油醛 C3磷酸戊糖途徑磷酸戊糖途徑第一階段第一階段 第第二二階階段段 5-磷酸木酮糖磷酸木酮糖 C55-磷酸木酮糖磷酸木酮糖 C57-磷酸景天糖磷酸景天糖 C73-磷酸甘油醛磷酸甘油醛 C34-磷酸赤蘚糖磷酸赤蘚糖 C46-磷酸果糖磷酸果糖 C66-磷酸果糖磷酸果糖 C63-磷酸磷酸甘油醛甘油醛 C36-磷酸葡萄糖磷酸葡萄