Sanjanwala M, Sun G Y, Cutrera M A, MacQuarrie R A
School of Basic Life Sciences, University of Missouri, Kansas City 64110.
Arch Biochem Biophys. 1988 Sep;265(2):476-83. doi: 10.1016/0003-9861(88)90152-x.
Bovine heart muscle microsomes rapidly convert lysophosphatidylcholine (LPC) into phosphatidylcholine (PC) in the presence of oleoyl-CoA. Both substrates are incorporated into the product, although the rate of incorporation of radiolabel into PC from 1-[14C]palmitoyl-LPC was approximately threefold higher than the rate of incorporation from [14C]oleoyl-CoA. Furthermore, the rate of incorporation of radiolabel from [14C]LPC was stimulated fivefold by the presence of oleoyl-CoA. These results demonstrate the presence of both acyl-CoA:1-acyl-sn-glycero-3-phosphocholine O-acyltransferase (EC 2.3.1.23) and an LPC:LPC transacylase (EC 3.1.1.5) in microsomes. Separation of the two enzymatic activities and purification of the acyltransferase was achieved by a procedure involving extraction with 3-[3-cholamidopropyl)dimethylammonio)-1-propanesulfonate detergent and chromatography on DEAE-cellulose, Reactive blue agarose, and Matrex gel green A. The isolated acyltransferase was a single species of 64,000 Da as judged by polyacrylamide gel electrophoresis in the presence of dodecyl sulfate. The substrate specificity of the enzyme was studied by using a series of lysophospholipids as acyl acceptors and acyl-CoA derivatives as acyl donors. The enzyme was catalytically active with LPC as acyl acceptor but displayed little or no activity with lysophosphatidylethanolamine, lysophosphatidylinositol, or lysophosphatidylserine. Of the LPC derivatives tested, the highest activity was obtained with 1-palmitoyl-LPC. Wider specificity was exhibited for the nature of the acyl donor, for which arachidonoyl-CoA, linoleoyl-CoA, and oleoyl-CoA were highly active substrates. These properties of the acyltransferase are in accord with a role of the enzyme in determining the composition of PC in myocardium.
在油酰辅酶A存在的情况下，牛心肌微粒体可迅速将溶血磷脂酰胆碱（LPC）转化为磷脂酰胆碱（PC）。两种底物都被掺入产物中，尽管从1-[14C]棕榈酰-LPC掺入PC中的放射性标记速率比从[14C]油酰辅酶A掺入的速率高约三倍。此外，油酰辅酶A的存在使[14C]LPC的放射性标记掺入速率提高了五倍。这些结果表明微粒体中存在酰基辅酶A：1-酰基-sn-甘油-3-磷酸胆碱O-酰基转移酶（EC 2.3.1.23）和LPC：LPC转酰基酶（EC 3.1.1.5）。通过用3-[（3-胆酰胺丙基）二甲基铵基]-1-丙烷磺酸盐洗涤剂萃取并在DEAE-纤维素、活性蓝琼脂糖和Matrex凝胶绿A上进行色谱分离的方法，实现了两种酶活性的分离和酰基转移酶的纯化。在十二烷基硫酸钠存在下通过聚丙烯酰胺凝胶电泳判断，分离出的酰基转移酶是一种分子量为64,000 Da的单一蛋白。通过使用一系列溶血磷脂作为酰基受体和酰基辅酶A衍生物作为酰基供体来研究该酶的底物特异性。该酶以LPC作为酰基受体时具有催化活性，但对溶血磷脂酰乙醇胺、溶血磷脂酰肌醇或溶血磷脂酰丝氨酸几乎没有或没有活性。在所测试的LPC衍生物中，1-棕榈酰-LPC的活性最高。对于酰基供体的性质表现出更广泛的特异性，花生四烯酰辅酶A、亚油酰辅酶A和油酰辅酶A是其高活性底物。酰基转移酶的这些特性与该酶在决定心肌中PC组成方面的作用一致。
