Lageweg W, Wanders R J, Tager J M
Department of Pediatrics, University of Amsterdam, The Netherlands.
Eur J Biochem. 1991 Mar 14;196(2):519-23. doi: 10.1111/j.1432-1033.1991.tb15844.x.
We have investigated the palmitic acid (C16:0) and cerotic acid (C26:0) activating activities in rat-liver microsomes and peroxisomes. The activation of the two fatty acids showed similar dependencies on ATP and coenzyme A, reflected in about equal apparent Km values both in microsomes and peroxisomes. In microsomes and peroxisomes similar apparent Km values for palmitic acid were found (15 microM and 22.8 microM, respectively), whereas apparent Km values for cerotic acid were 8.4 microM and 1.0 microM in microsomes and peroxisomes, respectively. The activation of cerotic acid was found to be inhibited to a progressively greater extent by increasing concentrations of 1-pyrenedecanoic acid (P10) as compared to the activation of palmitic acid, both in microsomes and peroxisomes. The inhibition by P10 of palmitic acid activation and cerotic acid activation was non-competitive in both organelles. From the observation that P10 activation is not affected by palmitic acid and cerotic acid, we conclude that P10 is activated by a distinct enzyme. Furthermore, our results are in accordance with earlier suggestions that activation of cerotic acid is brought about by an enzyme distinct from the palmitoyl-CoA synthetase.
我们研究了棕榈酸（C16:0）和蜡酸（C26:0）在大鼠肝脏微粒体和过氧化物酶体中的活化活性。两种脂肪酸的活化对ATP和辅酶A表现出相似的依赖性，在微粒体和过氧化物酶体中的表观Km值大致相等。在微粒体和过氧化物酶体中发现棕榈酸的表观Km值相似（分别为15 microM和22.8 microM），而蜡酸在微粒体和过氧化物酶体中的表观Km值分别为8.4 microM和1.0 microM。与棕榈酸的活化相比，在微粒体和过氧化物酶体中，随着1-芘癸酸（P10）浓度的增加，蜡酸的活化受到的抑制程度逐渐增大。在这两种细胞器中，P10对棕榈酸活化和蜡酸活化的抑制均为非竞争性。从P10的活化不受棕榈酸和蜡酸影响这一观察结果，我们得出结论，P10是由一种独特的酶活化的。此外，我们的结果与早期的推测一致，即蜡酸的活化是由一种不同于棕榈酰辅酶A合成酶的酶引起的。
