Hansen Kristella, Varvas Külliki, Järving Ivar, Samel Nigulas
Department of Chemistry, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
Department of Chemistry, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
Comp Biochem Physiol B Biochem Mol Biol. 2014 Aug;174:45-52. doi: 10.1016/j.cbpb.2014.05.004. Epub 2014 Jun 16.
Prostaglandins (PG) have been shown to play important physiological roles in insects and marine invertebrates, yet the knowledge of their biosynthetic pathways is often lacking. Recently, we described cyclooxygenases in two amphipod crustaceans, Gammarus sp. and Caprella sp. In the present study, we report the cloning and characterization of prostaglandin E synthases (PGES) from the same organisms. The amphipod membrane-bound PGES-2-type enzymes share about 40% of the amino acid sequence identity with human mPGES-2, contain a conserved Cys110-x-x-Cys113 motif and have very low heme-binding affinity. The recombinant enzymes purified in the absence of dithiothreitol specifically catalyze the isomerization of PGH2 into PGE2. The PGES activity is increased in the presence of reduced glutathione and inhibited with a sulfhydryl group inhibitor. We assume that the amphipod mPGES-2, unlike in their mammalian counterparts, is responsible for PGE2 synthesis, not only in vitro but also in vivo.
前列腺素（PG）已被证明在昆虫和海洋无脊椎动物中发挥重要的生理作用，但人们对其生物合成途径的了解往往不足。最近，我们描述了两种双足甲壳动物（Gammarus sp.和Caprella sp.）中的环氧化酶。在本研究中，我们报告了来自相同生物的前列腺素E合酶（PGES）的克隆和表征。双足膜结合型PGES-2类酶与人类mPGES-2的氨基酸序列同一性约为40%，含有保守的Cys110-x-x-Cys113基序，且血红素结合亲和力非常低。在没有二硫苏糖醇的情况下纯化的重组酶特异性催化PGH2异构化为PGE2。PGES活性在还原型谷胱甘肽存在下增加，并被巯基抑制剂抑制。我们推测，与哺乳动物中的情况不同，双足mPGES-2不仅在体外而且在体内都负责PGE2的合成。
