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【目的】二氢硫辛酸酰胺脱氢酶(Dihydrolipoamide dehydrogenase,Lpd)是铜绿假单胞菌(Pseudomonas aeruginosa)表面的一种纤溶酶原(Plasminogen,Plg)受体,旨在研究Lpd与脂蛋白(a)[Lipoprotein(a),Lp(a)]以及Plg之间的相互作用。【方法】用大肠杆菌表达rLpd及其突变分子(rLpd K476A、rLpd K477A、rLpdΔKKR),用酶联免疫吸附实验(ELISA)、亲和色谱层析及Western blot等技术检测rLpd及其突变分子与Lp(a)、Plg的相互作用。【结果】ELISA及亲和色谱层析实验结果表明,rLpd可以与Lp(a)结合但不与LDL结合,Lp(a)与rLpdΔKKR的结合能力显著低于其与rLpd的结合能力。1 mmol/L的赖氨酸类似物6-氨基己酸(EACA)对rLpd与Lp(a)的结合有显著的抑制作用。1 000μg/L的Lp(a)对rLpd与Plg的结合起到显著的抑制作用。【结论】Lpd能够与Lp(a)特异性结合,其476和477两个相邻的赖氨酸残基是与Lp(a)结合的主要位点,Lp(a)可以竞争性地抑制rLpd与Plg的结合。
【Objective】 Dihydrolipoamide dehydrogenase (Dihydrolipoamide dehydrogenase, Lpd) is a Plasminogen (Plg) receptor on the surface of Pseudomonas aeruginosa, and aims to study the relationship between Lpd and lipoprotein (a) [Lipoprotein (a), Lp (a)] and Plg. 【Method】 The rLpd and its mutated molecules (rLpd K476A, rLpd K477A and rLpdΔKKR) were expressed in Escherichia coli. The expression of rLpd and its mutants were detected by ELISA, affinity chromatography and Western blot. (a), Plg interaction. 【Results】 The results of ELISA and affinity chromatography showed that rLpd could bind to Lp (a) but not to LDL. The binding ability of Lp (a) to rLpdΔKKR was significantly lower than that of rLpd. The 1 mmol / L lysine analog 6-aminocaproic acid (EACA) significantly inhibited the binding of rLpd to Lp (a). Lp (a) at 1 000 μg / L significantly inhibited the binding of rLpd to Plg. 【Conclusion】 Lpd can specifically bind to Lp (a). Two adjacent lysine residues, 476 and 477, are the major sites of Lp (a) binding. Lp (a) can competitively inhibit rLpd Combination with Plg.