The subcellular distribution of carnitine acyltransferases in mammalian liver and kidney. A new peroxisomal enzyme.
The subcellular distribution of carnitine acyltransferases in mammalian liver and kidney. A new peroxisomal enzyme.
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DOI：
10.1016/s0021-9258(19)43946-x
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发表时间：
1973-05
期刊：
影响因子：
--
通讯作者：
M. Markwell;E. McGroarty;L. Bieber;N. Tolbert
中科院分区：
文献类型：
--
作者：
M. Markwell;E. McGroarty;L. Bieber;N. Tolbert
采用蔗糖密度梯度等密度离心法分离大鼠和猪肝、肾细胞器，并进行标记酶定位。肉毒碱棕榈酰转移酶被证明是唯一的线粒体酶。在肝脏中，大约52%的肉毒碱乙酰转移酶活性是线粒体，14%过氧化物酶体，34%位于富含脂质的膜部分。微粒体是这最后一部分的一个组成部分，当通过差速离心分离时，含有肉毒碱乙酰转移酶活性。这种酶以前没有报道过在过氧化物酶体中。肝脏过氧化物酶体中的肉毒碱乙酰转移酶的比活性是线粒体或微粒体中的两到三倍。部分分馏破碎的大鼠肝脏过氧化物酶体成核心，膜，和可溶性基质表明，肉毒碱乙酰转移酶有一个类似的分布的基质酶，过氧化氢酶。在大鼠和猪肾的梯度，肉毒碱乙酰转移酶主要被发现在线粒体组分。通过三个独立的试验证实了肝脏组分中的肉毒碱乙酰转移酶活性--从乙酰辅酶A中1（-）-肉毒碱依赖性释放辅酶A（CoA）、鉴定14 C标记的反应产物乙酰肉毒碱和从CoA中1（-）-乙酰肉毒碱依赖性形成乙酰辅酶A。在肝过氧化物酶体和微粒体中，辛酰辅酶A的肉毒碱酰基转移酶活性约等于乙酰辅酶A的活性。在线粒体中，辛酰辅酶A的活性是乙酰辅酶A的六倍。
Liver and kidney organelles from rat and pig were separated by isopycnic sucrose density gradient centrifugation and located by marker enzymes. Carnitine palmitoyltransferase was shown to be exclusively a mitochondrial enzyme. In liver, approximately 52% of carnitine acetyltransferase activity was mitochondrial, 14% peroxisomal, and 34% located in a lipid-rich membranous fraction. Microsomes were a component of this last fraction and, when isolated by differential centrifugation, contained carnitine acetyltransferase activity. This enzyme has not previously been reported to be in peroxisomes. The specific activity of carnitine acetyltransferase in liver peroxisomes was two to three times greater than in the mitochondria or microsomes. Partial fractionation of broken rat liver peroxisomes into core, membranes, and the soluble matrix indicated that carnitine acetyltransferase had a similar distribution to the matrix enzyme, catalase. In gradients of rat and pig kidney, carnitine acetyltransferase was found primarily in the mitochondrial fractions. This enzyme was also not detected in microbodies, mitochondria, or microsomes from plants.Carnitine acetyltransferase activity in liver fractions was confirmed by three separate assays—an 1(-)-carnitine-dependent release of coenzyme A (CoA) from acetyl-CoA, identification of the14C-labeled reaction product acetylcarnitine, and the 1(-)-acetylcarnitine-dependent formation of acetyl-CoA from CoA. Carnitine acyltransferase activity for octanoyl-CoA in hepatic peroxisomes and microsomes was about equal to activity for acetyl-CoA. In the mitochondria, activity for octanoyl-CoA was six times greater than for acetyl-CoA.