中国寄生虫学与寄生虫病杂志

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毛首鞭形线虫丝氨酸蛋白酶抑制剂TtSerpin1对蛋白酶的抑制作用

司徒永立1,2, 邵正1, 邓莉1, 隋细香1, 李海舰1,3, 许琴英1, 何庆丰1, 彭礼飞1,2,3*   

  1.  1 广东医科大学寄生虫学暨临床寄生虫检验学教研室, 湛江 524023; 2 广东医科大学病原生物学研究所, 湛江 524023; 3 广东省医学分子诊断重点实验室, 东莞 523808
  • 出版日期:2017-08-30 发布日期:2017-09-14

Study on the protease inhibitory activity of TtSerpin1, a serine protease inhibitor from Trichuris trichiura

SITU Yong-li1,2, SHAO Zheng1, DENG Li1, SUI Xi-xiang1, LI Hai-jian1,3, XU Qin-ying1, #br# HE Qing-feng1, PENG Li-fei1,2,3*   

  1. 1 Department of Parasitology and Clinical Parasitology, Guangdong Medical University, Zhanjiang 524023, China; 2 Institute of Pathogen Biology, Guangdong Medical University, Zhanjiang 524023, China; 3 Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan 523808, China
  • Online:2017-08-30 Published:2017-09-14

摘要:

目的 原核表达、分离纯化毛首鞭形线虫(Trichuris trichiura)丝氨酸蛋白酶抑制剂1(TtSerpin1), 并观察其对蛋白酶的抑制作用。 方法 从毛首鞭形线虫成虫cDNA中扩增TtSerpin1编码序列(GenBank 登录号为MF401634), 将其连接入原核表达载体, 构建重组质粒pET32a-sumo/TtSerpin1。将重组质粒转化入大肠埃希菌(Escherichia coli)BL21(DE3)中, 用异丙基-β-D-硫代半乳糖苷诱导TtSerpin1融合蛋白表达。表达的包涵体蛋白经变性、复性、镍亲和层析纯化、SUMO蛋白酶酶切融合标签后获得rTtSerpin1。用发色底物法检测其对人组织蛋白酶G、中性粒细胞弹性蛋白酶、蛋白酶3、纤溶酶和胰蛋白酶, 猪胰蛋白酶、胰弹性蛋白酶及牛α-胰糜蛋白酶的抑制作用。 结果 成功构建了重组质粒pET32a-sumo/TtSerpin1, 并在E. coli中成功表达。表达产物主要为包涵体, 复性、纯化后的rTtSerpin1具有较好的蛋白酶抑制活性。1 000 nmol/L的rTtSerpin1对人组织蛋白酶G(100 nmol/L)、中性粒细胞弹性蛋白酶(10 nmol/L)、蛋白酶3(200 nmol/L), 猪胰弹性蛋白酶(10 nmol/L), 牛α-胰糜蛋白酶(1 nmol/L)的蛋白酶活性抑制率分别为60.89%、82.84%、21.21%、58.32%、96.98%, 但对人纤溶酶、胰蛋白酶及猪胰蛋白酶抑制活性较弱。rTtSerpin1对人组织蛋白酶G及中性粒细胞弹性蛋白酶的抑制常数(Ki)分别为(949.80±91.51)、(242.70±53.41)nmol/L。 结论 rTtSerpin1对多种丝氨酸蛋白酶具有较强抑制作用。

关键词: 毛首鞭形线虫, 丝氨酸蛋白酶抑制剂, 原核表达, 组织蛋白酶G, 中性粒细胞弹性蛋白酶, 蛋白酶3

Abstract:

Objective To express, identify and characterize the serine protease inhibitory activity of Trichuris trichiura serine protease inhibitor 1(TtSerpin1). Methods The nucleotide sequence encoding for TtSerpin1 (GenBank No.MF401634) was amplified from adult T. trichiura cDNA and ligated into pET32a-sumo vector to construct the recombinant plasmid pET32a-sumo/TtSerpin1. The positive recombinant plasmid was transferred into Escherichia coli BL21 (DE3) and expressed with IPTG induction. After denaturation, refolding, purification by Ni-NTA resin affinity chromatography and cleaving fusion tag by SUMO protease on the resin, a single stage chromogenic assay was used to detect the inhibitory activity of rTtSerpin1 against serine proteases. Results The recombinant plasmid pET32a-sumo/TtSerpin1 was constructed successfully. The fusion protein expressed in E. coli was insoluble and became aggregated as the inclusion body. The purified TtSerpin1 after refolding showed inhibitory activity against serine proteases. At a concentration of 1 000 nmol/L, rTtSerpin1 inhibited the enzymatic activity of human cathepsin G (100 nmol/L), human neutrophil elastase (10 nmol/L), human proteinase 3 (200 nmol/L), porcine pancreatic elastase (10 nmol/L) and bovine pancreatic α-chymotrypsin (1 nmol/L) by approximately 60.89%, 82.84%, 21.21%, 58.32%, and 96.98%, respectively, but it showed a weaker inhibitory activity against human trypsin (1 nmol/L), porcine trypsin (1 nmol/L) and human fibrinolytic enzyme (5 nmol/L). rTtSerpin1 inhibited human cathepsin G and neutrophil elastase with a Ki value of (949.80±91.51) and (242.70±53.41) nmol/L, respectively. Conclusion TtSerpin1 shows an inhibitory activity against multiple serine proteases.

Key words: Trichuris trichiura, Serine protease inhibitor, Prokaryotic expression, Cathepsin G, Neutrophil elastase, Proteinase 3