Direct desaturation of eicosatrienoyl lecithin to arachidonoyl lecithin by rat liver microsomes.
Direct desaturation of eicosatrienoyl lecithin to arachidonoyl lecithin by rat liver microsomes.
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大鼠肝微粒体将二十碳三烯酰卵磷脂直接去饱和为花生四烯酰卵磷脂。
DOI：
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发表时间：
1977
影响因子：
4.8
通讯作者：
M. Kates
中科院分区：
文献类型：
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作者：
E. Pugh;M. Kates
从大鼠肝脏中提取的一种微粒体酶系统被证明能够在还原的吡啶核苷酸和氧气存在下催化1-acyl-2-[14C]eicosatrienoyl-sn-glycero-3-phosphorylcholine到1-acyl-2-[14C]arachidonoyl-sn-glycerophosphorylcholine.的去饱和。这种去饱和度与时间呈线性关系，与微粒体蛋白浓度成正比，并且没有明显破坏卵磷脂底物。微粒体酶系统也将去饱和1，2-di-[14C]eicosatrienoyl-sn-glycero-3-phosphorylcholine和[14C]二十碳三烯酰辅酶A，但在没有三磷酸腺苷、镁离子和辅酶A的情况下，不能使游离的[1-14C]二十碳三烯酸去饱和。1-acyl-2-[14C]eicosatrienoyl-glycerophosphorylcholine和[14C]二十碳三烯酰辅酶A的去饱和度依赖于氧和NADH或NADPH，并被氰化物抑制，但不被一氧化碳抑制，表明细胞色素b5而不是P450参与了这一过程。饥饿48h并补充脱脂饲料的大鼠，二十碳三烯酰-甘油磷酸胆碱去饱和酶和二十碳三烯-辅酶A去饱和酶活性均升高。这些数据表明，存在一条合成花生四烯酸的新路线，即通过将二十碳三烯基卵磷脂脱饱和生成花生四烯酰卵磷脂。
A microsomal enzyme system from rat liver was shown to catalyze desaturation, in presence of reduced pyridine nucleotides and oxygen, of 1-acyl-2-[14C]eicosatrienoyl-sn-glycero-3-phosphorylcholine to 1-acyl-2-[14C]arachidonoyl-sn-glycerophosphorylcholine. This desaturation was linear with time and proportional to microsomal protein concentration, and proceeded with no significant breakdown of the lecithin substrate. The microsomal enzyme system will also desaturate 1,2-di-[14C]eicosatrienoyl-sn-glycero-3-phosphorylcholine and [14C]eicosatrienoyl-CoA, but not free [1-14C]eicosatrienoic acid in the absence of ATP, Mg2+, and CoA. Desaturation of 1-acyl-2-[14C]eicosatrienoyl-glycerophosphorylcholine as well as [14C]eicosatrienoyl-CoA was dependent on oxygen and either NADH or NADPH, and was inhibited by cyanide but not by carbon monoxide, indicating the involvement of cytochrome b5 and not P450. The activity of both eicosatrienoyl-glycerophosphorylcholine desaturase and the eicosatrienoyl-CoA desaturase was increased in rats that had been starved for 48 h and refed a fat-free diet. These data indicate the existence of a new route to synthesis of arachidonate, namely, by desaturation of eicosatrienoyl lecithin to arachidonoyl lecithin.