Human plasminogen Kringle 5 is known to pose a more potent anti-angiogenesis effect by inducing endothelial cell apoptosis. Our previous studies have identified the peptide IGNSNTL as a binding sequence of Kringle 5 using Ph.D.-7 phage display peptide library and enzyme-linked immunosorbent assay. Here, eleven proteins were screened and summarized by BLAST, laminin α3 chain G1 domain (LG1) was considered as the most potential receptor based on E value and domain function. The specific interaction of them was directly revealed through ligand blot and a strong concentration-dependent manner occurred between them (Ka 4.30 × 105 L mol-1) in frontal chromatography observation. Moreover, R10A/P83R substitution Kringle 5 decreased the affinity capacity to LG1. Furthermore, a remarkable conformational change from random coil3 to α helix and α1 helix to random coil were observed to the structural compactness and stability for LG1. Surface loops and coils also showed fluctuations up to some extent, giving the binding surface greater flexibility and correspondingly allowing for induced-fit binding, which was -23.87 kcal mol-1 of the free energy with electrostatic force as a main driver. Taken together, not only effective theoretical prediction and experiment validated that LG1 is receptor of Kringle 5, but also give an new perspective of the binding mechanism of Kringle 5 and its specific receptor and could facilitate the development of novel agent targeted toward pathologic angiogenesis.

中文翻译：

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通过生物特异性技术和分子动力学，人层粘连蛋白α3链G1结构域是人内皮细胞上纤溶酶原Kringle 5的受体。

已知人纤溶酶原Kringle 5通过诱导内皮细胞凋亡而具有更强的抗血管生成作用。我们以前的研究已经使用Ph.D.-7噬菌体展示肽库和酶联免疫吸附测定法将肽IGNSNTL鉴定为Kringle 5的结合序列。在这里，通过BLAST筛选并总结了11种蛋白质，基于E值和域功能，层粘连蛋白α3链G1域（LG1）被认为是最有潜力的受体。通过配体印迹直接揭示了它们的特异性相互作用，并且在额线色谱观察中它们之间发生了强烈的浓度依赖性方式（Ka 4.30×105 L mol-1）。此外，R10A / P83R取代Kringle 5降低了对LG1的亲和力。此外，从LG1的结构致密性和稳定性观察到从无规卷曲3到α螺旋和从α1螺旋到无规螺旋的显着构象变化。表面环和线圈也显示出一定程度的波动，使结合表面具有更大的柔韧性，并相应地允许感应配合结合，这是静电力作为主要驱动力的自由能的-23.87 kcal mol-1。综上，不仅有效的理论预测和实验验证了LG1是Kringle 5的受体，而且为Kringle 5及其特异性受体的结合机理提供了新的视角，并且可以促进针对病理性血管生成的新型药物的开发。表面环和线圈也显示出一定程度的波动，使结合表面具有更大的柔韧性，并相应地允许感应配合结合，这是静电力作为主要驱动力的自由能的-23.87 kcal mol-1。综上，不仅有效的理论预测和实验验证了LG1是Kringle 5的受体，而且为Kringle 5及其特异性受体的结合机理提供了新的视角，并且可以促进针对病理性血管生成的新型药物的开发。表面环和线圈也显示出一定程度的波动，使结合表面具有更大的柔韧性，并相应地允许感应配合结合，这是静电力作为主要驱动力的自由能的-23.87 kcal mol-1。综上，不仅有效的理论预测和实验验证了LG1是Kringle 5的受体，而且为Kringle 5及其特异性受体的结合机理提供了新的视角，并且可以促进针对病理性血管生成的新型药物的开发。