Characterization and role of cis/trans isomerase of unsaturated fatty acids in bacteria.

假单胞菌的无细胞提取物。菌株E-3在游离酸中催化9顺-十六烯酸[16：1(9c)]和16：1(9c)酯化生成磷脂酰乙醇胺(PE)的sn-1和2位，生成9-反式十六碳烯酸[16：1(9t)]。经105,000×g，60分钟的超速离心法将无细胞提取物Wa！J分离为可溶性(胞液)和膜部分。胞浆组分催化游离的16：1(9c)异构化。另一方面，在膜组分的存在下，16：1(9c)酯化产物异构化为PE。一个催化16：1(9c)异构化反应的胞液组分(组分I)和另一个酯化16：1(9c)异构化所需的组分(组分II)在配有凝胶过滤柱的高效液相色谱系统上是完全分离的。这些结果表明，假单胞菌属(Psedomonas sp.)菌株E-3至少含有两种“顺式/反式”异构酶，组分I经DEAE-Toyota opearl和ButyToyota opearl柱层析纯化，凝胶过滤柱层析分离得到两个组分，这两个组分是16：1(9c)到16：1(9t)异构化所必需的。该酶的最适温度为1oC，并在低温下保持了较高的活性。

Cell-free extract of PseudoNonas sp. strain E-3 catalyzed the conversion of 9cis-hexadecenoib acid[16 : 1(9c)]in a free acid and 16 : 1(9c)esterified to both the sn-1 and 2 positions of phosphatidylethanolamine(PE)to 9-trans-hexadecenoic acid[16 : 1(9t)]. The cell-free extract wa!j separated into the soluble(cytosolic)and membrane fractions by the ultracentrifugation at 105, 000 x g for 60 min. The cytosol fraction catalyzed the isomerization of the free 16 : 1(9c). On the other hand, it isomerized 16 : 1(9c)esterified to PE in the presence of the membrane fraction. One cytosolic component(component I)that catalyze the isomerization of free 16 : 1(9c)and the other(component II)that is needed for the isomerization of esterified 16 : 1(9c)were completely separable one another with a high-performance liquid chromatographic system equipped Kith a gel filtration column. These results suggest that Psedomonas sp. strain E-3 contains at least two types of "Cis/trans isometases.Component I was purified by column chromatography with DEAE-Toyopearl and ButyToyopearl. Purified enzyme was separated into two components by gel-filtration column chromatography. These two components ' were essentially needed for isomeriation of 16 : 1(9c)to 16 : 1(9t). The enzyme has a temperature optimum at ^oC and maintained significant activities at subzero temperatures.