Walker J, Crowley P, Moreman A D, Barrett J
Department of Biological Sciences, University of Wales at Aberystwyth, Dyfed, UK.
Mol Biochem Parasitol. 1993 Oct;61(2):255-64. doi: 10.1016/0166-6851(93)90071-5.
cDNA clones encoding a 28-kDa subunit glutathione S-transferase (GST) from Schistosoma mansoni (Sm28GST) and a 26-kDa subunit GST from Schistosoma japonicum (Sj26GST) have been expressed in bacterial systems. The recombinant proteins were purified to homogeneity by batch-wash glutathione-agarose affinity chromatography and their biochemical properties investigated. Gel filtration chromatography indicated that both recombinant GSTs are homodimeric proteins. Resolution of Sm28GST and Sj26GST by chromatofocusing in the ranges pH 9-6 and pH 7-4 gave pI estimates of 7.4 and 5.0, respectively. Kinetic analyses suggested that both Sm28GST and Sj26GST operate via a sequential bisubstrate catalytic mechanism. Sm28GST and Sj26GST displayed a mosaic of mammalian Alpha-, Mu- and Pi-type substrate specificities and inhibitor sensitivities. However, multivariate analysis suggests that Sm28GST has an overall catalytic homology with mammalian Mu class GSTs, whilst the enzymatic properties of Sj26GST appear to constitute a hybridisation of Mu and Alpha class features. Both recombinant GSTs interact with a range of hydrophobic ligands including haematin and related compounds, bile acids and several anthelmintics. Sm28GST and Sj26GST possess relatively limited selenium-independent glutathione peroxidase activities, but are able to catalyse the glutathione conjugation of members of the trans,trans-alka-2,4-dienal, trans-alk-2-enal and 4-hydroxyalk-2-enal series of reactive carbonyls (known secondary products of lipid peroxidation).
编码曼氏血吸虫28 kDa亚基谷胱甘肽S-转移酶（Sm28GST）和日本血吸虫26 kDa亚基谷胱甘肽S-转移酶（Sj26GST）的cDNA克隆已在细菌系统中表达。通过批量洗涤谷胱甘肽-琼脂糖亲和层析将重组蛋白纯化至同质，并对其生化特性进行了研究。凝胶过滤层析表明，两种重组谷胱甘肽S-转移酶均为同二聚体蛋白。在pH 9 - 6和pH 7 - 4范围内通过聚焦层析分离Sm28GST和Sj26GST，得到的等电点估计值分别为7.4和5.0。动力学分析表明，Sm28GST和Sj26GST均通过顺序双底物催化机制起作用。Sm28GST和Sj26GST表现出哺乳动物α-、μ-和π-型底物特异性及抑制剂敏感性的组合。然而，多变量分析表明，Sm28GST与哺乳动物μ类谷胱甘肽S-转移酶具有总体催化同源性，而Sj26GST的酶学特性似乎构成了μ类和α类特征的杂交。两种重组谷胱甘肽S-转移酶均与一系列疏水配体相互作用，包括血红素及相关化合物、胆汁酸和几种驱虫药。Sm28GST和Sj26GST具有相对有限的非硒依赖性谷胱甘肽过氧化物酶活性，但能够催化反式、反式-alka-2,4-二烯醛、反式-alk-2-烯醛和4-羟基alk-2-烯醛系列活性羰基化合物（已知的脂质过氧化二级产物）的谷胱甘肽共轭反应。
