第23章柠檬酸循环.ppt

主要内容
TCA准备阶段
TCA循环阶段
TCA产能计算
TCA的调节
TCA双重作用
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TCA背景知识
1、为什么称为柠檬酸循环、三羧酸循环(Tricarboxylic acid cycle, TCA) 、Krebs循环?
在有氧的情况下,葡萄糖酵解产生的丙酮酸氧化脱羧形成乙酰CoA。乙酰CoA经一系列氧化、脱羧,最终生成C2O和H2O并产生能量的过程,称为柠檬酸循环,亦称为三羧酸循环(tricarboxylic acid cycle), 简称TCA循环。(德国)正式提出的,所以又称Krebs循环。
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“It is convenient to use a brief term for the kind of scheme. Its essential feature is the periodic formation of a number of di- and tricarboxylic acids. As there is no term which would serve as mon denominator for all the various acids, it seemed reasonable to name the cycle
after one, or some, of its characteristic and specific acids. It was from such considerations that the term "citric acid cycle" was proposed in 1937.”(Hans A. Krebs, The citric acid cycle, Nobel Lecture, December 11, 1953)
Krebs, 1901-1981
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Brief history of TCA
The first major investigation into the intermediary metabolism of oxidation was that of Thunberg, who examined systematically the oxidizability anic substances in isolated animal tissues. Between 1906 and 1920 he tested the oxidation of over anic substances, chiefly in muscle tissue. He discovered the rapid oxidation of the salts of a number of acids, such as lactate(乳酸盐), inate(琥珀酸盐), fumarate(延胡索酸盐), malate(苹果酸盐), citrate(柠檬酸盐), and glutamate(谷氨酸盐).
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In 1932, Krebs was studying the rates of oxidation of anic acids by kidney and liver tissue. Only a few of substances were active in these experiments---notably inate, fumarate, acetate, malate, and citrate.
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An important development came from the laboratory of Szent-yi of Szegedin 1935, who confirmed on pigeon breast muscle the rapid oxidation of the C4-dicarboxylic acids - inic, fumaric, malic, and oxaloacetic acids - and arrived at the new conclusion that those dicarboxylic acids were linked by an enzymatic pathway that was important for aerobic metabolism.
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A decisive contribution to the field was made in March 1937 by Martius and Knoop, who discovered α-ke