A 615 bp full length cDNA encoding a Teladorsagia circumcincta glutathione transferase (TcGST) was cloned, expressed in Escherichia coli and the recombinant protein purified and its kinetic properties determined. The predicted protein consisted of 205 amino acids and was present as a single band of about 24 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TcGST with homologues from other helminths showed that the highest identity of 53-68% with haem-binding nematode proteins designated as members of the nu class of GSTs. Substrate binding sites and conserved regions were identified and were generally conserved. The predicted 3-dimensional structures of TcGST and HcGST revealed highly open binding cavities typical of this class of GST, considered to allow greater accessibility to diverse ligands compared with other classes of GST. At 25 °C, the optimum pH for TcGST activity was pH 7, the V_max was 1535 ± 33 nmoles.min^-1. mg^-1 protein and the apparent K_m for the substrate 1-chloro-2,4-dinitrobenzene (CDNB) was 0.22 ± 0.01 mM (mean ± SD, n = 2). Antibodies in both serum and saliva from field-immune, but not nematode-naïve, sheep, recognised recombinant TcGST in enzyme-linked immunosorbent assays. The recognition of the recombinant protein by antibodies generated by exposure of sheep to the native enzyme indicates similar antigenicity of the two proteins. These findings could aid in the design of novel drugs and vaccine antigens for economically important parasites of livestock.

克隆了一个长615 bp的cDNA，编码了一个圆环斜纹肌谷胱甘肽转移酶（Tc GST），在大肠杆菌中表达，并纯化了重组蛋白并确定了其动力学特性。预测的蛋白质由205个氨基酸组成，在SDS-PAGE上以约24 kDa的单条带存在。Tc GST的蛋白质序列与其他蠕虫的同源物的多重比对表明，与被指定为nu类GST成员的血红素结合线虫蛋白的最高同一性为53-68％。底物结合位点和保守区被鉴定并且通常是保守的。Tc GST和Hc的预测3维结构GST揭示了此类GST中典型的高度开放的结合腔，与其他类型的GST相比，GST被认为可以更好地接近各种配体。在25°C下，Tc GST活性的最佳pH为pH 7，V _max为1535±33 nmoles.min ^-1。毫克^-1蛋白质，底物1-氯-2,4-二硝基苯（CDNB）的表观K _m为0.22±0.01 mM（平均值±SD，n = 2）。来自野外免疫但未感染线虫的绵羊血清和唾液中的抗体都可识别重组Tc酶联免疫吸附测定中的GST。通过羊暴露于天然酶产生的抗体对重组蛋白的识别表明两种蛋白的相似抗原性。这些发现可以帮助设计用于牲畜经济上重要的寄生虫的新药和疫苗抗原。