第二十五章 戊糖磷酸途及糖异生途径
第二十五章 戊糖磷酸途及糖异生途径
武糖髒醱苿弪 In most animal tissues, the major catabolic fate of glucose 6-phosphate is glycolytic breakdown to pyruvate, much of which is then oxidized via the citric acid cycle ultimately leading to the formation ofATP. a Glucose 6-phosphate does have other catabolic fates. however which lead to specialized products needed by the cell. Of particular importance in some tissues is the oxidation of glucose 6-phosphate to pentose phosphates by the pentose phosphate pathway
一、戊糖磷酸途径 ◼ In most animal tissues, the major catabolic fate of glucose 6-phosphate is glycolytic breakdown to pyruvate, much of which is then oxidized via the citric acid cycle, ultimately leading to the formation of ATP. ◼ Glucose 6-phosphate does have other catabolic fates, however, which lead to specialized products needed by the cell. Of particular importance in some tissues is the oxidation of glucose 6-phosphate to pentose phosphates by the pentose phosphate pathway
■(一)戊糖磷酸途径的发现 在组织中添加酵解抑制剂碘乙酸(抑制3-P-甘油醛脱 氢酶)或氟化物(抑制烯醇化酶)等,葡萄糖仍可被 消耗;并且c更容易氧化成cO2;发现了6-P-葡萄糖 脱氢酶和6-P-葡萄糖酸脱氢酶及NADP+;发现了五碳 糖、六碳糖和七碳糖;说明葡萄糖还有其他代谢途径 (1931-1951) 1953年阐述了磷酸戊糖途径( pentose phosphate pathway),简称PP途径,他叫磷酸己糖支路;磷酸 葡萄糖酸氧化途径、已糖单磷酸旁路( hexose monophosphate shut HMS) 主要发生在肝脏、脂肪组织、哺乳期的乳腺、肾上腺 皮质、性腺、骨髓和红细胞等
(一)戊糖磷酸途径的发现 ◼ 在组织中添加酵解抑制剂碘乙酸（抑制3-P-甘油醛脱 氢酶）或氟化物（抑制烯醇化酶）等，葡萄糖仍可被 消耗；并且C1更容易氧化成CO2；发现了6-P-葡萄糖 脱氢酶和6-P-葡萄糖酸脱氢酶及NADP+；发现了五碳 糖、六碳糖和七碳糖；说明葡萄糖还有其他代谢途径 （1931-1951）。 ◼ 1953年阐述了磷酸戊糖途径（pentose phosphate pathway)，简称PPP途径，也叫磷酸己糖支路；磷酸 葡萄糖酸氧化途径、已糖单磷酸旁路(hexose monophosphate shut HMS) 。 ◼ 主要发生在肝脏、脂肪组织、哺乳期的乳腺、肾上腺 皮质、性腺、骨髓和红细胞等
■〔二)磷酸戊糖途径的反应 ■磷酸戊糖途径在细胞液中进行,全过程 分为不可逆的氧化阶段和可逆的非氧化 阶段。 氧化反应阶段:生成 NADPH及CO2; 非氧化反应阶段:一系列基团的转移
(二)磷酸戊糖途径的反应 ◼ 磷酸戊糖途径在细胞液中进行，全过程 分为不可逆的氧化阶段和可逆的非氧化 阶段。 ◼ 氧化反应阶段: 生成NADPH及CO2； ◼ 非氧化反应阶段:一系列基团的转移
Pentose Phosphate Pathway CHOH (adnt Hexose monophosphate shunt etc Coo HO-C-H Ok O NADP+ NADPH CH, OPi CH,OPi H2o H-C-OH NADPH NADP CH,OH H-C-OH HO-C-H C=0 HOPi OH Ce-PAH L2M2HC一 oH t-P-ER20YN H-C-OH X-5-P OH H-C-OH H-C-OH G-6-P CHOPi -5-P2w H 6-P-gluconolactone CHaOPi 6-P-gluconate RU-5-P G-6-P H-C-OH CHoH RlN/Ne CH2OH Ho→C R-5-P CHoo @⊙ H-C-OH H H-C-OH H-C-OH H-C-OH CH2OPi F-6-P H CHOPi H-C-OH H-C-OH X-5-P H-C-OH H-C-OH 配e CHOPi CH,OPi CH,OP JNnnL52aAa Sedoheptulose F-6-P GA-3-P 7-P H-C-OH H H-C-OH H-C-OH H H-C-oH CHaOPi CH,OP H-C-OH HO-C-H R-5-P GA-3-P CH OPi H-C-OH Erytrose-4A-P & A 2& 199, X-5-P