Zammit V A, Corstorphine C G, Kolodziej M P
Hannah Research Institute, Scotland, U.K.
Biochem J. 1989 Oct 1;263(1):89-95. doi: 10.1042/bj2630089.
The functional molecular sizes of the protein(s) mediating the carnitine palmitoyltransferase I (CPT I) activity and the [14C]malonyl-CoA binding in purified outer-membrane preparations from rat liver mitochondria were determined by radiation-inactivation analysis. In all preparations tested the dose-dependent decay in [14C]malonyl-CoA binding was less steep than that for CPT I activity, suggesting that the protein involved in malonyl-CoA binding may be smaller than that catalysing the CPT I activity. The respective sizes computed from simultaneous analysis for molecular-size standards exposed under identical conditions were 60,000 and 83,000 DA for malonyl-CoA binding and CPT I activity respectively. In irradiated membranes the sensitivity of CPT activity to malonyl-CoA inhibition was increased, as judged by malonyl-CoA inhibition curves for the activity in control and in irradiated membranes that had received 20 Mrad radiation and in which CPT activity had decayed by 60%. Possible correlations between these data and other recent observations on the CPT system are discussed.
通过辐射失活分析确定了介导肉碱棕榈酰转移酶I（CPT I）活性以及在大鼠肝脏线粒体纯化外膜制剂中[14C]丙二酰辅酶A结合的蛋白质的功能分子大小。在所有测试制剂中，[14C]丙二酰辅酶A结合的剂量依赖性衰减比CPT I活性的衰减平缓，这表明参与丙二酰辅酶A结合的蛋白质可能比催化CPT I活性的蛋白质小。在相同条件下对分子大小标准品进行同步分析计算得出，丙二酰辅酶A结合和CPT I活性的各自大小分别为60,000和83,000道尔顿。通过对照膜以及接受20兆拉德辐射且CPT活性衰减60%的辐照膜中活性的丙二酰辅酶A抑制曲线判断，在辐照膜中CPT活性对丙二酰辅酶A抑制的敏感性增加。讨论了这些数据与CPT系统其他近期观察结果之间可能的相关性。
