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次黄嘌呤单核苷酸脱氢酶(IMPDH)是金黄色葡萄球菌(S.aureus)表面的纤溶酶原(Plg)受体之一,它可以通过赖氨酸结合位点(LBS)与Plg相结合。脂蛋白(a)[Lp(a)]中的载脂蛋白(a)[Apo(a)]与Plg有很高的同源性,即两者的Kringle结构域都含有LBS,其中Apo(a)的KIV10含有强的LBS。因此本实验提出了Lp(a)应该能够与S.aureus表面的Plg受体相结合,进而可能竞争性抑制S.aureus与Plg结合的假说。本研究克隆了S.aureus的IMPDH基因,酶切后将其连接到表达载体pASK-IBA37中,并在大肠杆菌BL21中表达了该重组蛋白(rIMPDH)。通过酶联免疫吸附试验(ELISA)、亲和色谱层析及Western blot对rIMPDH与Lp(a)的相互作用机制进行了研究。结果表明rIMPDH可以通过LBS与Lp(a)和rKIV10发生特异性结合,而且一定浓度的赖氨酸类似物6-氨基己酸(EACA)可以抑制这种结合,然而本研究并未发现Lp(a)和rKIV10对rIMPDH与Plg的相互作用有明显的抑制。
Hypoxanthine mononucleotide dehydrogenase (IMPDH) is one of the plasminogen (Plg) receptors on the surface of S. aureus that can be activated by lysine binding sites (LBS) and Plg combined. Apolipoprotein (a) [Apo (a)] in lipoprotein (a) [Lp (a)] has a high homology with Plg, ie both Kringle domains contain LBS, ) KIV10 contains strong LBS. Therefore, we hypothesize that Lp (a) should bind to Plg receptor on the surface of S. aureus, which may competitively inhibit the binding of S. aureus to Plg. In this study, the IMPDH gene of S.aureus was cloned and ligated into the expression vector pASK-IBA37. The recombinant protein (rIMPDH) was expressed in E. coli BL21. The interaction mechanism between rIMPDH and Lp (a) was studied by enzyme-linked immunosorbent assay (ELISA), affinity chromatography and Western blot. The results showed that rIMPDH could specifically bind Lp (a) and rKIV10 through LBS, and a certain concentration of lysine analogue 6-aminocaproic acid (EACA) could inhibit this binding. However, we did not find Lp (a ) And rKIV10 significantly inhibited the interaction between rIMPDH and Plg.