Interaction of factor XIII subunits
Interaction of factor XIII subunits
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DOI：
10.1182/blood-2013-10-533596
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发表时间：
2014-03-13
期刊：
影响因子：
20.3
通讯作者：
Muszbek, Laszlo
中科院分区：
文献类型：
--
作者：
Katona, Eva;Penzes, Krisztina;Muszbek, Laszlo
凝血因子XIII （FXIII）是由2个催化a亚基（FXIII- a(2)）和2个保护/抑制B亚基（FXIII-B-2）组成的异四聚体。FXIII-B是一种由10个sushi结构域组成的马赛克蛋白，可显著延长循环中催化亚基的寿命，并防止其在浆态条件下缓慢的渐进激活。本研究对2个FXIII亚基之间的相互作用进行了生物化学研究。利用表面等离子体共振技术和酶联免疫吸附测定型结合试验，在10(-10)m范围内建立了相互作用的平衡解离常数（K-d）。根据测量的Kd，计算出血浆中约有1%的FXIII-A(2)应以游离形式存在。通过测量FXIII-A(2)和fxiii - B(2)免疫缺失血浆样品中的FXIII-A(2)，实验证实了这一值。游离血浆FXIII-A2具有功能活性，当被凝血酶和Ca2+激活时，可交联纤维蛋白。在FXIII亚基浓度低得多的脑脊液和泪液中，约80%的FXIII- a(2)以自由形式存在。一种单克隆抗FXIII-B抗体与重组的FXIII-B第一和第二sushi结构域发生反应，其抗原表位定位在第二sushi结构域的96 ~ 103位。
Coagulation factor XIII (FXIII) is a heterotetramer consisting of 2 catalytic A subunits (FXIII-A(2)) and 2 protective/inhibitory B subunits (FXIII-B-2). FXIII-B, a mosaic protein consisting of 10 sushi domains, significantly prolongs the lifespan of catalytic subunits in the circulation and prevents their slow progressive activation in plasmatic conditions. In this study, the biochemistry of the interaction between the 2 FXIII subunits was investigated. Using a surface plasmon resonance technique and an enzyme-linked immunosorbent assay-type binding assay, the equilibrium dissociation constant (K-d) for the interaction was established in the range of 10(-10) M. Based on the measured Kd, it was calculated that in plasma approximately 1% of FXIII-A(2) should be in free form. This value was confirmed experimentally by measuring FXIII-A(2) in plasma samples immunodepleted of FXIII-A(2)B(2). Free plasma FXIII-A2 is functionally active, and when activated by thrombin and Ca2+, it can cross-link fibrin. In cerebrospinal fluid and tears with much lower FXIII subunit concentrations, >80% of FXIII-A(2) existed in free form. A monoclonal anti-FXIII-B antibody that prevented the interaction between the 2 subunits reacted with the recombinant combined first and second sushi domains of FXIII-B, and its epitope was localized to the peptide spanning positions 96 to 103 in the second sushi domain.