Gavino G R, Gavino V C
Department of Nutrition, Université de Montreal, Quebec, Canada.
Lipids. 1991 Apr;26(4):266-70. doi: 10.1007/BF02537135.
The activity of the overt form of rat liver mitochondrial carnitine palmitoyltransferase or CPT0 (EC 2.3.1.21) towards different fatty acid substrates was studied. The following non-esterified fatty acids (NEFA) and their CoA esters in the presence of 1% bovine serum albumin (BSA) were tested: 16:0, 18:0, 18:1, 18:2, 18:3 omega 3, 20:4, 20:5 omega 3 and 22:6 omega 3. The data fit a square hyperbolic model for enzyme catalysis (p less than 0.001, non-linear regression). Asymptotic Vmax and K0.5, substrate concentration at one-half Vmax, were calculated using total concentrations of acyl-CoA, or unbound concentrations of NEFA. BSA was found to act as a true substrate reservoir for NEFA in that the dissociation of the NEFA-BSA complex was 10-330 times faster than the CPT0 reaction. Regardless of form (NEFA or CoA ester), 18:3 omega 3 gave the highest, while 22:6 omega 3 and 18:0 gave the lowest rates of acylcarnitine synthesis. Except for 18:3 omega 3 and 18:2, Vmax for NEFA was generally lower than for acyl-CoA, with the greatest differences observed for 20:4, 20:5 omega 3 and 22:6 omega 3, suggesting that acyl-CoA synthesis may also be important in the control of the entry of these fatty acids into the mitochondria. The data provide an enzymatic rationale for the relatively low content of 18:3 omega 3 in esterified lipid.
研究了大鼠肝脏线粒体肉碱棕榈酰转移酶（CPT0，EC 2.3.1.21）公开形式对不同脂肪酸底物的活性。在1%牛血清白蛋白（BSA）存在的情况下，测试了以下非酯化脂肪酸（NEFA）及其辅酶A酯：16:0、18:0、18:1、18:2、18:3 ω-3、20:4、20:5 ω-3和22:6 ω-3。数据符合酶催化的双曲平方模型（p＜0.001，非线性回归）。使用酰基辅酶A的总浓度或NEFA的未结合浓度计算渐近Vmax和K0.5（Vmax一半时的底物浓度）。发现BSA作为NEFA的真正底物储存库，因为NEFA-BSA复合物的解离比CPT0反应快10 - 330倍。无论形式（NEFA或辅酶A酯）如何，18:3 ω-3的酰基肉碱合成速率最高，而22:6 ω-3和18:0的速率最低。除18:3 ω-3和18:2外，NEFA的Vmax通常低于酰基辅酶A，在20:4、20:5 ω-3和22:6 ω-3中观察到最大差异，这表明酰基辅酶A合成在控制这些脂肪酸进入线粒体方面可能也很重要。这些数据为酯化脂质中18:3 ω-3含量相对较低提供了酶学依据。
