目的·制备牙周致病相关坦纳菌编码的丝氨酸蛋白酶抑制剂（serine protease inhibitor，Serpin），分析其抑制靶蛋白酶的特异性及其结构特征。方法·通过氨基酸序列分析，选择人类口腔微生物组数据库（eHOMD）中的Serpin，将其转入大肠埃希菌中进行重组表达；采用镍离子亲和层析等方法制备重组蛋白，分析其抑制丝氨酸蛋白酶的特异性，并通过结构生物学手段解析其三维空间结构。结果·在坦纳菌中发现一个新的且活性中心P1残基为甲硫氨酸的Serpin，将其命名为Tannerpin-M，并成功地从大肠埃希菌BL21（DE3）中制备了高纯度的重组蛋白。进一步的活性检测结果表明重组Tannerpin-M可以有效地与粒细胞来源的蛋白酶（人中性粒细胞弹性蛋白酶、组织蛋白酶G和蛋白酶3）、胰弹性蛋白酶以及激肽释放酶1（KLK1）、KLK7等6种蛋白酶形成SDS稳定的共价复合物，其中Tannerpin-M抑制KLK7的二级反应速率常数为4.25×10⁴ L/（mol·s）。解析分辨率为2.4 ?（1 ?=0.1 nm）的Tannerpin-M松弛态构象的晶体结构，结果显示Tannerpin-M具有显著延长的反应中心环，可以发生经典的抑制型Serpin从紧张态向松弛态转变的构象变化。结论·口腔致病菌编码的Tannerpin-M是一个典型的抑制型Serpin，其可以有效抑制粒细胞释放的丝氨酸蛋白酶，提示该口腔致病菌可能以此机制来抵抗人体免疫系统的攻击。

Objective ·To prepare a serine protease inhibitor (Serpin) derived from Tannerella which is associated with periodontosis, and analyze its specificity in inhibiting target proteases and its structural characteristics. Methods ·Through amino acid sequence analysis, a Serpin from the human oral microbiome database (eHOMD) was selected and expressed in Escherichia coli. The recombinant protein was purified using methods such as nickel ion affinity chromatography. Its specificity in inhibiting serine proteases was analyzed, followed by an analysis of its three-dimensional spatial structure using structural biology methods. Results ·A novel Serpin, named Tannerpin-M, with methionine as the active center P1 residue, was identified, and a high-purity recombinant protein was successfully prepared from Escherichia coli BL21 (DE3). Further activity testing demonstrated that recombinant Tannerpin-M could effectively form SDS-stable covalent complexes with proteases derived from granulocytes (human neutrophil elastase, cathepsin G, and proteinase 3), as well as with other proteases including kallikrein 1 (KLK1), KLK7, and elastase. Tannerpin-M inhibited KLK7 with a second-order association rate constant of 4.12×10⁴ L/(mol·s). The crystal structure of Tannerpin-M in its relaxed state conformation was resolved at a resolution of 2.4 ? (1 ?=0.1 nm). It revealed that Tannerpin-M possessed a significantly elongated reactive center loop and could undergo the classical conformational transition from a stressed to a relaxed state. Conclusion ·Tannerpin-M, derived from oral pathogenic bacteria, is a typical inhibitory Serpin, and can effectively inhibit the serine protease released by granulocytes, by which it may protect the oral pathogenic bacteria from attacks of the human immune system.