Edwards M R, Bird M I, Saggerson E D
Biochem J. 1985 Aug 15;230(1):169-79. doi: 10.1042/bj2300169.
The overt form of carnitine palmitoyltransferase (CPT1) in rat liver and heart mitochondria was inhibited by DL-2-bromopalmitoyl-CoA and bromoacetyl-CoA. S-Methanesulphonyl-CoA inhibited liver CPT1. The inhibitory potency of DL-2-bromopalmitoyl-CoA was 17 times greater with liver than with heart CPT1. Inhibition of CPT1 by DL-2-bromopalmitoyl-CoA was unaffected by 5,5'-dithiobis-(2-nitrobenzoic acid) or (in liver) by starvation. In experiments in which DL-2-bromopalmitoyl-CoA displaced [14C]malonyl-CoA bound to liver mitochondria, the KD (competing) was 25 times the IC50 for inhibition of CPT1 providing evidence that the malonyl-CoA-binding site is unlikely to be the same as the acyl-CoA substrate site. Bromoacetyl-CoA inhibition of CPT1 was more potent in heart than in liver mitochondria and was diminished by 5,5'-dithiobis-(2-nitrobenzoic acid) or (in liver) by starvation. Bromoacetyl-CoA displaced bound [14C]malonyl-CoA from heart and liver mitochondria. In heart mitochondria this displacement was competitive with malonyl-CoA and was considerably facilitated by L-carnitine. In liver mitochondria this synergism between carnitine and bromoacetyl-CoA was not observed. It is suggested that bromoacetyl-CoA interacts with the malonyl-CoA-binding site of CPT1. L-Carnitine also facilitated the displacement by DL-2-bromopalmitoyl-CoA of [14C]malonyl-CoA from heart, but not from liver, mitochondria. DL-2-Bromopalmitoyl-CoA and bromoacetyl-CoA also inhibited overt carnitine octanoyl-transferase in liver and heart mitochondria. These findings are discussed in relation to inter-tissue differences in (a) the response of CPT1 activity to various inhibitors and (b) the relationship between high-affinity malonyl-CoA-binding sites and those sites for binding of L-carnitine and acyl-CoA substrates.
大鼠肝脏和心脏线粒体中肉碱棕榈酰转移酶（CPT1）的显性形式受到DL-2-溴棕榈酰辅酶A和溴乙酰辅酶A的抑制。S-甲磺酰辅酶A抑制肝脏CPT1。DL-2-溴棕榈酰辅酶A对肝脏CPT1的抑制效力比对心脏CPT1的抑制效力大17倍。DL-2-溴棕榈酰辅酶A对CPT1的抑制不受5,5'-二硫代双（2-硝基苯甲酸）的影响，在肝脏中也不受饥饿的影响。在DL-2-溴棕榈酰辅酶A取代与肝脏线粒体结合的[14C]丙二酰辅酶A的实验中，KD（竞争）是抑制CPT1的IC50的25倍，这表明丙二酰辅酶A结合位点不太可能与酰基辅酶A底物位点相同。溴乙酰辅酶A对CPT1的抑制在心脏中比在肝脏线粒体中更有效，并且在肝脏中5,5'-二硫代双（2-硝基苯甲酸）或饥饿会使其减弱。溴乙酰辅酶A从心脏和肝脏线粒体中取代结合的[14C]丙二酰辅酶A。在心脏线粒体中，这种取代与丙二酰辅酶A具有竞争性，并且L-肉碱可大大促进这种取代。在肝脏线粒体中未观察到肉碱与溴乙酰辅酶A之间的这种协同作用。有人认为溴乙酰辅酶A与CPT1的丙二酰辅酶A结合位点相互作用。L-肉碱也促进了DL-2-溴棕榈酰辅酶A从心脏线粒体而非肝脏线粒体中取代[14C]丙二酰辅酶A。DL-2-溴棕榈酰辅酶A和溴乙酰辅酶A也抑制肝脏和心脏线粒体中显性的肉碱辛酰转移酶。本文结合组织间差异讨论了这些发现，这些差异包括（a）CPT1活性对各种抑制剂的反应，以及（b）高亲和力丙二酰辅酶A结合位点与L-肉碱和酰基辅酶A底物结合位点之间的关系。
