Increase of the activity state and loss of total activity of the branched-chain 2-oxo acid dehydrogenase in rat diaphragm during incubation.
Increase of the activity state and loss of total activity of the branched-chain 2-oxo acid dehydrogenase in rat diaphragm during incubation.
复制标题
孵化期间大鼠膈肌中支链2-含氧酸脱氢酶的活性状态增加和总活性丧失。
DOI：
10.1042/bj2240491
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
J. Veerkamp
中科院分区：
文献类型：
--
作者：
A. Wagenmakers;J. Schepens;J. Veerkamp
实际和总支链2-含氧酸脱氢酶活性在喂养和饥饿大鼠的培养隔膜匀浆中测定。在 Krebs-Ringer 缓冲液中孵育增加了活性状态，但导致总活性显着损失。棕榈酸酯氧化速率和柠檬酸合酶活性在孵育时没有显着变化。饥饿的肌肉在孵化 15 分钟后（而不是在 30 和 60 分钟后）表现出更高程度的激活，并且总活动损失较小。使用转氨酶抑制剂氨基氧乙酸酯进行的实验证实，在体外培养的饥饿大鼠的隔膜中，内源氨基酸对氧化前体库的贡献也较小。这些现象共同导致饥饿大鼠的肌肉中 14C 标记的支链氨基酸和 2-含氧酸产生的 14CO2 高于进食大鼠的肌肉。高浓度的支链 2-含氧酸以及 2-氯-4-甲基戊酸、辛酸或酮体的存在，增加了脱氢酶复合物的活化程度；葡萄糖和丙酮酸没有影响。观察到的这些代谢物活性状态的变化与它们与孵育的半膈中支链2-含氧酸氧化的相互作用进行了讨论。
Actual and total branched-chain 2-oxo acid dehydrogenase activities were determined in homogenates of incubated diaphragms from fed and starved rats. Incubation in Krebs-Ringer buffer increased the activity state, but caused considerable loss of total activity. Palmitate oxidation rates and citrate synthase activities did not significantly change on incubation. Starved muscles showed a higher extent of activation after 15 min of incubation (not after 30 and 60 min) and a smaller loss of total activity. Experiments with the transaminase inhibitor amino-oxyacetate confirm that the contribution of endogenous amino acids to the oxidation precursor pool is also smaller in diaphragms from starved rats on incubation in vitro. These phenomena together cause the higher 14CO2 production from 14C-labelled branched-chain amino acids and 2-oxo acids in muscles from starved than from fed rats. High concentrations of branched-chain 2-oxo acids, and the presence of 2-chloro-4-methyl-pentanoate, octanoate or ketone bodies, increase the extent of activation of the dehydrogenase complex; glucose and pyruvate had no effect. The observed changes of the activity state by these metabolites are discussed in relation to their interaction with branched-chain 2-oxo acid oxidation in incubated hemidiaphragms.