Studies on membrane-associated prostaglandin E synthase-2 with reference to production of 12L-hydroxy-5,8,10-heptadecatrienoic acid (HHT).
Studies on membrane-associated prostaglandin E synthase-2 with reference to production of 12L-hydroxy-5,8,10-heptadecatrienoic acid (HHT).
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DOI：
10.1016/j.bbrc.2008.01.029
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发表时间：
2008-03
影响因子：
3.1
通讯作者：
Kikuko Watanabe;S. Ito;Shozo Yamamoto
中科院分区：
文献类型：
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作者：
Kikuko Watanabe;S. Ito;Shozo Yamamoto
膜相关前列腺素（PG）E合成酶（mPGE合成酶）-2催化PGH 2主要转化为PGE 2。该酶被各种巯基试剂激活，包括二硫苏糖醇、二氢硫辛酸和谷胱甘肽，并且它不同于mPGE合酶-1和胞质PGE合酶，这两者都需要特异性谷胱甘肽。最近，其他研究者报道他们制备的含有血红素的mPGE合酶-2将PGH 2转化为12 L-羟基-5，8，10-十七碳三烯酸（HHT）而不是PGE 2 [T. Yamada，F. Takusagawa，Biochemistry 46（2007）8414-8424]。正如我们目前所研究的，根据他们的方法表达和纯化的血红素结合酶从PGH 2合成HHT，但也以减少的量合成PGE 2。而PGE合酶活性在50°C下5分钟完全丧失，HHT合酶活性甚至在100°C下5分钟仍保持。与此相反，当血红素结合的酶在二硫苏糖醇的存在下纯化，只有PGE 2产生，但基本上没有HHT被检测到。因此，天然mPGE合酶-2仅酶促催化PGH 2转化为PGE 2，而不催化转化为HHT，并且血红素不参与该反应。
Membrane-associated prostaglandin (PG) E synthase (mPGE synthase)-2 catalyzes the conversion of PGH2primarily to PGE2. The enzyme is activated by various sulfhydryl reagents including dithiothreitol, dihydrolipoic acid, and glutathione, and it is different from mPGE synthase-1 and cytosolic PGE synthase, both of which require specifically glutathione. Recently, other investigators reported that their preparation of mPGE synthase-2 containing heme converted PGH2to 12L-hydroxy-5,8,10-heptadecatrienoic acid (HHT) rather than to PGE2[T. Yamada, F. Takusagawa, Biochemistry 46 (2007) 8414–8424]. As we examined presently, the heme-bound enzyme expressed and purified according to their method synthesized HHT from PGH2, but also PGE2in a decreased amount. Whereas the PGE synthase activity was completely lost at 50°C for 5min, the HHT synthase activity remained even at 100°C for 5min. In contrast, when the heme-bound enzyme was purified in the presence of dithiothreitol, only PGE2was produced, but essentially no HHT was detected. Thus, native mPGE synthase-2 enzymatically catalyzes only the conversion of PGH2to PGE2, but not to HHT, and heme is not involved in this reaction.