些开始的器异生反应过 table 20-2 Sequential Reactions in Gluconeogenesis Starting from Pyruvate Pyruvate HCO3+ ATP- oXaloacetate ADP+P+H 2 Oxaloacetate GTP= phosphoenolpyruvate CO 2+ GDP 2 Phosphoenolpyruvate H20= 2-phosphoglycerate 2 2-Phosphoglycerate 3-phosphoglycerate 2 3-Phosphoglycerate+ ATP= 1, 3-bisphosphoglycerate + ADP+H+ 2 1, 3-Bisphosphoglycerate+ NADH H= glyceraldehyde 3-phosphate+ NAD+ P 2 Glyceraldehyde 3-phosphate dihydroxyacetone phosphate Glyceraldehyde 3-phosphate dihydroxyacetone phosphate fructose 1, 6-bisphosphate Fructose 1, 6-bisphosphate H20- fructose 6-phosphate+ P Fructose 6-phosphate= glucose 6-phosphate Glucose 6-phosphate+ H20- glucose P Sum: 2 Pyruvate+4ATP+ 2GTP 2NADH +4H20- glucose 4ADP + 2GDP+ 6P,+ 2NAD*+2H The bypass reactions are in red; all other reactions are NADH consumed in the glyceraldehyde 3-phosphate reversible steps of glycolysis. The figures at the right indicate dehydrogenase reaction(the conversion of lactate to pyruvate that the reaction is to be counted twice, because two three in the cytosol or the transport of reducing equivalents from carbon precursors are required to make a molecule of glucose. mitochondria to the cytosol in the form of malate)are not Note that the reactions required to replace the cytosolic considered in this summary
丙酮酸开始的糖异生反应过程
唐醇解与牛不回 Enzymatic differences between glycolysis and gluconeogenesis Glycolysis Gluconeogenesis Hexokinase Glucose 6-phosphatase Phosphofructokinase Fructose 1, 6 diphosphatase Pyruvate carboxylase Pyruvate kinase Phosphoenolpyruvate carboxykinase
糖酵解与糖元异生的酶不同 Glycolysis Gluconeogenesis Hexokinase Glucose 6-phosphatase Phosphofructokinase Fructose 1,6- diphosphatase Pyruvate kinase Pyruvate carboxylase Phosphoenolpyruvate carboxykinase Enzymatic differences between glycolysis and gluconeogenesis
与酮酸生成和异生为 The stoichiometry of gluconeogenesis is 2 Pyruvate +4 atP +2 GTP +2 NADH +2 H,O glucose +4 ADP +2 GDP+6P+2NAD+ G 9 kcal /mol In contrast, the stoichiometry for the reversal of glycolysis is 2 Pyruvate+2ATP+2NADH+2H2O→→ glucose +2 ADP +2P;+2 NAD+ △G"=+20kcal/mol
丙酮酸生成和异生为糖 的能量关系
糖异生的生理意 维持血糖浓度 补充肝糖原 调节酸碱平衡
糖异生的生理意义 •维持血糖浓度 •补充肝糖原 •调节酸碱平衡
糖无异生的前体物质 1)凡可生成Py的物质,包括TCA中间物,但乙 酰CoA动物体不作为糖异生的前体; 2)大多氨基酸是生糖氨基酸,如Aa,Glu,Asp, Ser, cys, Gly, Arg, His, Thr, Pro, GIn, Asn, Met val等,分别代谢为丙酮酸、草酰乙酸、α-酮戊 二酸等进入糖异生; 3肌肉剧烈运动产生的大量乳酸; 4)反刍动物分解纤维素产生的乙酸、丙酸、丁 酸等 5)奇数脂肪酸分解产生的琥珀酰CoA等
糖元异生的前体物质 1) 凡可生成Py的物质，包括TCA中间物，但乙 酰CoA[动物体]不作为糖异生的前体； 2) 大多氨基酸是生糖氨基酸，如Ala, Glu, Asp, Ser, Cys, Gly, Arg, His, Thr, Pro, Gln, Asn, Met, Val等，分别代谢为丙酮酸、草酰乙酸、-酮戊 二酸等进入糖异生； 3) 肌肉剧烈运动产生的大量乳酸； 4) 反刍动物分解纤维素产生的乙酸、丙酸、丁 酸等； 5) 奇数脂肪酸分解产生的琥珀酰CoA等