Neumann-Schmidt S, Zierz S
Neurologische Universitätsklinik Bonn, Germany.
Neuromuscul Disord. 1991;1(4):253-60. doi: 10.1016/0960-8966(91)90098-d.
Carnitine acyltransferase activities were studied in normal human skeletal muscle and in muscle of three patients with carnitine palmitoyltransferase deficiency. Carnitine acetyltransferase (CAT), carnitine octanoyltransferase (COT), and carnitine palmitoyltransferase (CPT) were differentiated (i) by the use of the substrates acetyl-CoA, octanoyl-CoA, lauroyl-CoA, and palmitoyl-CoA, (ii) by the inhibitors malonyl-CoA, chlorpromazine, and dithio-bis-nitrobenzoic acid (DTNB), and (iii) by the solubilities of the carnitine acyltransferase activities after centrifugation at 48,000 g for 30 min. The results are consistent with the notion of three different carnitine acyltransferases in human skeletal muscle: a membrane-bound malonyl-CoA-sensitive CPT, a soluble malonyl-CoA-insensitive CAT, and a malonyl-CoA-sensitive COT that is not attached to the mitochondrial membrane. The different solubilities of the carnitine acyltransferases allow a clear differentiation of CPT from CAT and COT in homogenates of previously frozen muscle biopsies whereas a separate determination of CAT and COT is only partially possible. In patients with CPT deficiency total CPT activity was within the normal range but was abnormally inhibited by malonyl-CoA and chlorpromazine. Activities of carnitine acyltransferases with the substrates acetyl-CoA and octanoyl-CoA were normal indicating that the biochemical defect in CPT deficiency is confined to CPT without compensatory changes of CAT and COT.
在正常人体骨骼肌以及三名患有肉碱棕榈酰转移酶缺乏症患者的肌肉中研究了肉碱酰基转移酶的活性。通过以下方法区分肉碱乙酰转移酶（CAT）、肉碱辛酰转移酶（COT）和肉碱棕榈酰转移酶（CPT）：（i）使用乙酰辅酶A、辛酰辅酶A、月桂酰辅酶A和棕榈酰辅酶A作为底物；（ii）使用丙二酸单酰辅酶A、氯丙嗪和二硫代双硝基苯甲酸（DTNB）作为抑制剂；（iii）在48,000 g下离心30分钟后，根据肉碱酰基转移酶活性的溶解度进行区分。结果与人体骨骼肌中存在三种不同肉碱酰基转移酶的观点一致：一种与膜结合的、对丙二酸单酰辅酶A敏感的CPT，一种可溶性的、对丙二酸单酰辅酶A不敏感的CAT，以及一种对丙二酸单酰辅酶A敏感但不附着于线粒体膜的COT。肉碱酰基转移酶的不同溶解度使得在先前冷冻的肌肉活检匀浆中能够清晰地区分CPT与CAT和COT，而单独测定CAT和COT仅部分可行。在CPT缺乏症患者中，总CPT活性在正常范围内，但被丙二酸单酰辅酶A和氯丙嗪异常抑制。以乙酰辅酶A和辛酰辅酶A为底物的肉碱酰基转移酶活性正常，表明CPT缺乏症的生化缺陷仅限于CPT，而CAT和COT没有代偿性变化。
