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第 19 章 糖酵解

第 19 章 糖酵解. The committing step. One subunit of the tetrameric phosphofructokinase-1 (PFK-1). Regulatory ADP. The level of F-2,6-BP is controlled by the relative activity of PFK-2 and FBPase-2, which are located in one polypeptide chain and whose activities are regulated

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第 19 章 糖酵解

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  1. 第19章 糖酵解

  2. The committing step One subunit of the tetrameric phosphofructokinase-1 (PFK-1) Regulatory ADP

  3. The level of F-2,6-BP is controlled by the relative activity of PFK-2 and FBPase-2, which are located in one polypeptide chain and whose activities are regulated by glucagon-stimulated phosphorylation.

  4. C-1 no longer carries a large positive charge: hydride ion leaves readily Phosphorolysis (磷酸解作用) Energy-rich intermediate (thioester) Proposed action mechanism Of glyceraldehyde 3-P dehydrogenase Inactive enzyme Iodoacetate 碘醋酸

  5. Pyruvate is decarboyxlated With the help of TPP, a coenzyme of pyruvate decarboxylase during ethanol fermentation

  6. 糖酵解的调节 • 糖酵解代谢途径的调节主要是通过各种变构剂对三个关键酶进行变构调节。 1. 己糖激酶或葡萄糖激酶: 葡萄糖激酶是肝脏调节葡萄糖吸收的主要的关键酶。

  7. - - 己糖激酶及葡萄糖激酶的变构剂 G-6-P 长链脂肪酸 己糖激酶 hexokinase 葡萄糖激酶 glucokinase

  8. + - 2. 磷酸果糖激酶-1(PKF-1): 磷酸果糖激酶-1是调节糖酵解代谢途径流量的主要因素。 ADP、AMP ,2,6-双磷酸果糖(由PKF-2) ATP,NADH,柠檬酸,长链脂肪酸 磷酸果糖激酶-1 phosphofructokinase-1

  9. A feedforward stimulation: Fru-6-P stimulate the synthesis and inhibits the hydrolysis of Fru-2,6-bisphosphate, which in turn stimulates PFK-1.

  10. Phosphofructokinase-1 (PFK-1) is regulated by many negative and positive effectors ADP Fructose 1,6- bisphosphate

  11. + - 3. 丙酮酸激酶: 1,6-双磷酸果糖 磷酸稀醇式丙酮酸 ATP,柠檬酸,长链脂肪酸,丙氨酸(肝) 丙酮酸激酶 pyruvate kinase

  12. 思考与练习 1、人血浆中的葡萄糖大约维持在5mM。而在肌肉细胞中的游离葡萄糖浓度要低得多。细胞内的葡萄糖浓度为什么如此之低?临床上常用静脉注射葡萄糖来补充病人食物来源,由于葡萄糖转换为葡萄糖-6-磷酸要消耗ATP的,那么临床上却不能直接静脉注射葡萄糖-6-磷酸呢? 2、 把C-1位用14C标记的葡萄糖与能进行糖酵解的无细胞提取物共同温育,标记物出现在丙酮酸的什么位置? 3、 增加以下各种代谢物的浓度对糖酵解有什么影响? (a)葡萄糖-6-磷酸 (b) 果糖-1.6-二磷酸 (C) 柠檬酸 (d) 果糖-2.6-二磷酸 4、 在严格的厌氧条件下酒精发酵过程中,使用放射性标记的碳源进行示踪原子实验。 (a)如果葡萄糖的第1个碳用14C标记,那么14C将出现在产物乙醇的哪个位置上? (b)在起始的葡萄糖分子的哪个位置上标记14C ,才能使乙醇发酵释放出的二氧化碳都是14C标记的14C 。

  13. 5、 当肌肉组织激烈活动时,与休息时相比需要更多的ATP。在骨骼肌里,例如兔子的腿肌或火鸡的飞行肌,需要的ATP几乎全部由有氧酵解反应产生的。假设骨骼肌缺乏乳酸脱氢酶,它们能否进行激烈的体力活动,即能否借助于酵解反应高速率生成ATP?5、 当肌肉组织激烈活动时,与休息时相比需要更多的ATP。在骨骼肌里,例如兔子的腿肌或火鸡的飞行肌,需要的ATP几乎全部由有氧酵解反应产生的。假设骨骼肌缺乏乳酸脱氢酶,它们能否进行激烈的体力活动,即能否借助于酵解反应高速率生成ATP? 6.为什么糖酵解途径中产生的NADH必须被氧化成NAD才能被在循环利用? 7.说出下列情况下积累的代谢物名称 (1)在能进行糖酵解的无细胞提取物中,乳酸脱氢酶被抑制; (2)在能进行发酵的酵母提取物中,乙醇脱氢酶被抑制;

  14. 8.由于砷酸在结构和化学性质上都与磷酸类似,很多需要磷酸的酶也能与砷酸结合。然而砷酸的有机化合物的稳定性比类似的磷酸化合物差,会被快速地水解。8.由于砷酸在结构和化学性质上都与磷酸类似,很多需要磷酸的酶也能与砷酸结合。然而砷酸的有机化合物的稳定性比类似的磷酸化合物差,会被快速地水解。 (a)如果用砷酸取代磷酸,对甘油醛—3—磷酸脱氢酶催化的反应有何影响? (b)如果用砷酸取代磷酸,对有机体的影响是什么?

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