OBSERVATIONS ON THE AFFINITY FOR CARNITINE, AND MALONYL-COA SENSITIVITY, OF CARNITINE PALMITOYLTRANSFERASE-I IN ANIMAL AND HUMAN-TISSUES - DEMONSTRATION OF THE PRESENCE OF MALONYL-COA IN NON-HEPATIC TISSUES OF THE RAT
OBSERVATIONS ON THE AFFINITY FOR CARNITINE, AND MALONYL-COA SENSITIVITY, OF CARNITINE PALMITOYLTRANSFERASE-I IN ANIMAL AND HUMAN-TISSUES - DEMONSTRATION OF THE PRESENCE OF MALONYL-COA IN NON-HEPATIC TISSUES OF THE RAT
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DOI：
10.1042/bj2140021
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发表时间：
1983-01-01
影响因子：
4.1
通讯作者：
FOSTER, DW
中科院分区：
文献类型：
--
作者：
MCGARRY, JD;MILLS, SE;FOSTER, DW
使用固定浓度的棕榈酰辅酶A (50μM)白蛋白(147μM)在来自动物或人类来源的8个组织的分离的线粒体中测量肉碱的需要量和肉碱棕榈酰转移酶I的丙二酰辅酶A敏感性。肉碱的 Km 跨越了 20 倍的范围，从成年大鼠和人胎肝脏中的约 35 μM 上升到狗心脏中的 700 μM。发现大鼠心脏、豚鼠肝脏和骨骼肌率、狗和人的中间值不断增加。相反，抑制酶活性50％所需的丙二酰辅酶A浓度从人和大鼠肝脏中的2-3μM范围下降至在肉毒碱表现出最高Km的组织中仅20nM。因此，对肉碱的需求和对丙二酰辅酶A的敏感性似乎呈负相关。肉碱棕榈酰转移酶 I 对棕榈酰辅酶 A 的 Km 在组织中相似，显示出对肉碱的需求存在很大差异。其他实验表明，除了肝脏之外，喂食大鼠的心脏和骨骼肌中也含有大量的丙二酰辅酶A，并且在所有 3 个组织中丙二酰辅酶 A 的水平都会随着饥饿而下降。尽管其在心脏和骨骼肌中的细胞内位置尚不清楚，但丙二酰辅酶A（或相关化合物）在某些情况下可能与非肝组织中的肉碱棕榈酰转移酶 I 相互作用，从而控制长脂肪酸氧化。
The requirement for carnitine and the malonyl-CoA sensitivity of carnitine palmitoyltransferase I were measured in isolated mitochondria from 8 tissues of animal or human origin using fixed concentrations of palmitoyl-CoA (50 .mu.M) albumin (147 .mu.M). The Km for carnitine spanned a 20-fold range, rising from about 35 .mu.M in adult rat and human fetal liver to 700 .mu.M in dog heart. Intermediate values of increasing magnitude were found for rat heart, guinea pig liver and skeletal muscle rate, dog and man. Conversely, the concentration of malonyl-CoA required for 50% suppression of enzyme activity fell from the region of 2-3 .mu.M in human and rat liver to only 20 nM in tissues displaying the highest Km for carnitine. Thus, the requirement for carnitine and sensitivity to malonyl-CoA appeared to be inversely related. The Km of carnitine palmitoyltransferase I for palmitoyl-CoA was similar in tissues showing large differences in requirement for carnitine. Other experiments established that, in addition to liver, heart and skeletal muscle of fed rats contain significant quantities of malonyl-CoA and that in all 3 tissues the level falls with starvation. Although its intracellular location in heart and skeletal muscle is not known, the possibility is raised that malonyl-CoA (or a related compound) could, under certain circumstances, interact with carnitine palmitoyltransferase I in nonhepatic tissues and thereby exert control over long fatty acid oxidation.