Furukawa-Stoffer Tara L, Boyle Riley M, Thomson Amber L, Sarna Magdalena A, Weselake Randall J
Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4 Canada.
Lipids. 2003 Jun;38(6):651-6. doi: 10.1007/s11745-003-1110-0.
Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT; EC 2.3.1.23) catalyzes the acyl-CoA-dependent acylation of lysophosphatidylcholine (LPC) to produce PC and CoA. LPCAT activity may affect the incorporation of fatty acyl moieties at the sn-2 position of PC where PUFA are formed and may indirectly influence seed TAG composition. LPCAT activity in microsomes prepared from microspore-derived cell suspension cultures of oilseed rape (Brassica napus L. cv Jet Neuf) was assayed using [1-14C]acyl-CoA as the fatty acyl donor. LPCAT activity was optimal at neutral pH and 35 degrees C, and was inhibited by 50% at a BSA concentration of 3 mg mL(-1). At acyl-CoA concentrations above 20 microM, LPCAT activity was more specific for oleoyl (18:1)-CoA than stearoyl (18:0)- and palmitoyl (16:0)-CoA. Lauroyl (12:0)-CoA, however, was not an effective acyl donor. LPC species containing 12:0, 16:0, 18:0, or 18:1 as the fatty acyl moiety all served as effective acyl acceptors for LPCAT, although 12:0-LPC was somewhat less effective as a substrate at lower concentrations. The failure of LPCAT to catalyze the incorporation of a 12:0 moiety from acyl-CoA into PC is consistent with the tendency of acyltransferases to discriminate against incorporation of this fatty acyl moiety at the sn-2 position of TAG from the seed oil of transgenic B. napus expressing a medium-chain thioesterase.
酰基辅酶A：溶血磷脂酰胆碱酰基转移酶（LPCAT；EC 2.3.1.23）催化溶血磷脂酰胆碱（LPC）的酰基辅酶A依赖性酰化反应，生成磷脂酰胆碱（PC）和辅酶A。LPCAT活性可能会影响多不饱和脂肪酸（PUFA）形成部位PC的sn-2位上脂肪酰基部分的掺入，并可能间接影响种子三酰甘油（TAG）的组成。使用[1-14C]酰基辅酶A作为脂肪酰基供体，对从油菜（甘蓝型油菜L. cv Jet Neuf）小孢子衍生的细胞悬浮培养物制备的微粒体中的LPCAT活性进行了测定。LPCAT活性在中性pH和35摄氏度时最佳，在牛血清白蛋白（BSA）浓度为3 mg mL(-1)时被抑制50%。在酰基辅酶A浓度高于20 microM时，LPCAT活性对油酰基（18:1）-辅酶A的特异性高于硬脂酰基（18:0）-辅酶A和棕榈酰基（16:0）-辅酶A。然而，月桂酰基（12:0）-辅酶A不是有效的酰基供体。含有12:0、16:0、18:0或18:1作为脂肪酰基部分的LPC种类均作为LPCAT的有效酰基受体，尽管12:0-LPC在较低浓度下作为底物的效果稍差。LPCAT无法催化酰基辅酶A中的12:0部分掺入PC，这与酰基转移酶在表达中链硫酯酶的转基因甘蓝型油菜种子油的TAG的sn-2位上歧视该脂肪酰基部分掺入的倾向一致。
