Regulation of the branched-chain 2-oxo acid dehydrogenase complex in hepatocytes isolated from rats fed on a low-protein diet.
Regulation of the branched-chain 2-oxo acid dehydrogenase complex in hepatocytes isolated from rats fed on a low-protein diet.
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从低蛋白饮食喂养的大鼠中分离出的肝细胞中支链 2-含氧酸脱氢酶复合物的调节。
DOI：
10.1042/bj2340285
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Powell,SM
中科院分区：
文献类型：
--
作者：
Harris,RA;Paxton,R;Goodwin,GW;Powell,SM
使用从喂食饲料或低蛋白 (8%) 饮食的大鼠中分离出的肝细胞来研究各种因素对通过支链 2-含氧酸脱氢酶复合物的流量的影响。还在肝细胞的无细胞提取物中测定了该复合物的活性。与从低蛋白饮食喂养的大鼠中分离的肝细胞相比，从食物喂养的大鼠中分离的肝细胞具有更高的通量率（3-甲基-2-氧代丁酸和4-甲基-2-氧代戊酸的脱羧率）。可氧化底物往往会抑制通过支链 2-含氧酸脱氢酶的通量，但从低蛋白饮食喂养的大鼠中分离出的肝细胞的抑制作用更大。 2-氯-4-甲基戊酸（支链 2-含氧酸脱氢酶激酶的抑制剂）、二氯乙酸（丙酮酸脱氢酶激酶和支链 2-含氧酸脱氢酶激酶的抑制剂）和二丁酰环 AMP（糖酵解抑制剂）是喂食大鼠肝细胞的支链含氧酸脱羧的有效刺激剂。低蛋白饮食，但对喂食饲料的大鼠的肝细胞影响不大。活性测量表明，在食物喂养的大鼠的肝细胞中，支链2-含氧酸脱氢酶复合物主要（96％）处于活性（去磷酸化）状态，但在低蛋白饮食喂养的大鼠的肝细胞中，支链2-含氧酸脱氢酶复合物仅部分（50％）处于活性状态。可氧化底物显着降低低蛋白饮食大鼠肝细胞中酶的活性状态，但对食物喂养大鼠肝细胞的影响要小得多。 2-Chloro-4-methylpentanoate和二氯乙酸增加了低蛋白饮食大鼠肝细胞中酶的活性状态，但对食物喂养大鼠肝细胞中酶的活性状态没有影响。结果表明，蛋白质饥饿大大增加了肝支链2-含氧酸脱氢酶复合物对共价修饰调节的敏感性。
Hepatocytes isolated from rats fed on a chow diet or a low-protein (8%) diet were used to study the effects of various factors on flux through the branched-chain 2-oxo acid dehydrogenase complex. The activity of this complex was also determined in cell-free extracts of the hepatocytes. Hepatocytes isolated from chow-fed rats had greater flux rates (decarboxylation rates of 3-methyl-2-oxobutanoate and 4-methyl-2-oxopentanoate) than did hepatocytes isolated from rats fed on the low-protein diet. Oxidizable substrates tended to inhibit flux through the branched-chain 2-oxo acid dehydrogenase, but inhibition was greater with hepatocytes isolated from rats fed on the low-protein diet. 2-Chloro-4-methylpentanoate (inhibitor of branched-chain 2-oxo acid dehydrogenase kinase), dichloroacetate (inhibitor of both pyruvate dehydrogenase kinase and branched-chain 2-oxo acid dehydrogenase kinase) and dibutyryl cyclic AMP (inhibitor of glycolysis) were effective stimulators of branched-chain oxo acid decarboxylation with hepatocytes from rats fed on a low-protein diet, but had little effect with hepatocytes from rats fed on chow diet. Activity measurements indicated that the branched-chain 2-oxo acid dehydrogenase complex was mainly (96%) in the active (dephosphorylated) state in hepatocytes from chow-fed rats, but only partially (50%) in the active state in hepatocytes from rats fed on a low-protein diet. Oxidizable substrates markedly decreased the activity state of the enzyme in hepatocytes from rats fed on a low-protein diet, but had much less effect in hepatocytes from chow-fed rats. 2-Chloro-4-methylpentanoate and dichloroacetate increased the activity state of the enzyme in hepatocytes from rats fed on a low-protein diet, but had no effect on the activity state of the enzyme in hepatocytes from chow-fed rats. The results indicate that protein starvation greatly increases the sensitivity of the hepatic branched-chain 2-oxo acid dehydrogenase complex to regulation by covalent modification.
影响因子：
3.9
作者：
M. Scrutton
通讯作者：
M. Scrutton