Physiological state and the sensitivity of liver mitochondrial outer membrane carnitine palmitoyltransferase to malonyl-CoA. Correlations with assay temperature, salt concentration and membrane lipid composition.
作者信息
Ghadiminejad I, Saggerson D
机构信息
Department of Biochemistry and Molecular Biology, University College London, U.K.
出版信息
Int J Biochem. 1992 Jul;24(7):1117-24. doi: 10.1016/0020-711x(92)90382-b.
Liver mitochondrial outer membranes were pre-exposed to media of low (20 mM phosphate) or high salt concentration (20 mM phosphate + 0.3 M KCl) before assay of carnitine palmitoyltransferase (CPT) at 25 degrees C. 2. With membranes from fed rats, exposure to high salt decreased sensitivity of CPT to malonyl-CoA whereas high salt increased sensitivity of CPT to malonyl-CoA in membranes from 48 hr-fasted rats. These changes were paralleled by alterations in the KD for high affinity binding of [14C]malonyl-CoA to outer membranes. 3. Decreasing the CPT assay temperatures from 25 to 10 degrees C caused qualitatively similar changes to those seen on exposure to high salt. 4. The relative content of sphingomyelin was increased 2-fold and 4-fold in liver mitochondrial outer membranes from fasted and diabetic rats respectively. Fasting had no effect on the content of cholesterol whereas diabetes decreased this by a third.
摘要
在25℃测定肉碱棕榈酰转移酶（CPT）之前，将肝线粒体外膜预先暴露于低盐（20 mM磷酸盐）或高盐浓度（20 mM磷酸盐 + 0.3 M KCl）的培养基中。2. 对于喂食大鼠的线粒体膜，暴露于高盐会降低CPT对丙二酸单酰辅酶A的敏感性，而对于禁食48小时大鼠的线粒体膜，高盐会增加CPT对丙二酸单酰辅酶A的敏感性。这些变化与[14C]丙二酸单酰辅酶A与外膜高亲和力结合的解离常数（KD）的改变平行。3. 将CPT测定温度从25℃降至10℃会引起与暴露于高盐时定性相似的变化。4. 禁食和糖尿病大鼠的肝线粒体外膜中鞘磷脂的相对含量分别增加了2倍和4倍。禁食对胆固醇含量没有影响，而糖尿病使胆固醇含量降低了三分之一。
