Plasminogen activator inhibitor-1 is locked in active conformation and polymerizes upon binding ligands neutralizing its activity.
Plasminogen activator inhibitor-1 is locked in active conformation and polymerizes upon binding ligands neutralizing its activity.
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DOI：
10.3892/ijmm.17.3.437
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发表时间：
2006-03
影响因子：
5.4
通讯作者：
J. Jankun;Z. Specht;Marian Szkudlarek;R. Greenfield;B. Gaikwad;L. Trifonov;J. Vaugeois;Ansari M. Aleem;V. Basrur;S. Selman;M. Zavodszky;E. Skrzypczak‐Jankun
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文献类型：
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作者：
J. Jankun;Z. Specht;Marian Szkudlarek;R. Greenfield;B. Gaikwad;L. Trifonov;J. Vaugeois;Ansari M. Aleem;V. Basrur;S. Selman;M. Zavodszky;E. Skrzypczak‐Jankun
纤溶酶原激活物抑制剂-1（派-1）是丝氨酸蛋白酶抑制剂超家族的成员，与其靶蛋白酶（如组织和尿激酶纤溶酶原激活剂）形成共价复合物。因此，派-1控制生理和病理性蛋白水解。在不同的疾病中观察到派-1的异常表达，这可以通过将蛋白水解恢复到正常生理水平来治疗。据报道，一些派-1抑制剂通过加速派-1转化为潜伏形式来中和其活性。我们已经发现了一些小的有机化学物质，它们也能中和派-1的活性，但机制不同。使用掺入派-1的反应中心环（RCL）中的NBD荧光探针[N，N ′-二甲基-N-（乙酰基）-N ′-（7-硝基苯-2-氧杂-1，3-二唑-4-基）]，我们测量了从活性形式转化为潜伏形式的动力学。出乎意料的是，我们发现派-1的一些抑制剂以其活性形式阻止这种丝氨酸蛋白酶抑制剂，而不是增加转化速度。使用对接计算，我们找到了这些化学品的两个可能的结合位点。这些位点靠近派-1 RCL的P1/P1'氨基酸。在该区域的结合可以抑制派-1，并且另外在RCL上产生空间障碍，使得在A3和A5链之间插入该环更加困难;因此取消了将该蛋白质转化为潜伏形式的必要步骤。另外，派-1抑制剂将一个派-1分子的RCL与另一个派-1分子的链3C和链4C或螺旋A和链1B区域连接，从而帮助聚合或稳定两者的连接。派-1的聚合通过将关键的RCL片段包封在所形成的派-1/派-1聚合物内来降低派-1活性。
Plasminogen activator inhibitor-1 (PAI-1), a member of the serpin super-family, forms a covalent complex with its target proteinases, such as tissue and urokinase plasminogen activators. Thus, PAI-1 controls the physiological and pathological proteolysis. An abnormal expression of PAI-1 has been observed in different diseases, which can be treated by returning the proteolysis back to normal physiological levels. It has been reported that some PAI-1 inhibitors neutralize its activity by accelerating the conversion of PAI-1 into a latent form. We have found small organic chemicals that also neutralize PAI-1 activity, but by a different mechanism. Using the NBD fluorescent probe [N,N'-dimethyl-N-(acetyl)-N'-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)] incorporated into the reactive center loop (RCL) of PAI-1, we measured the kinetics of conversion from an active to a latent form. Unexpectedly, we found that some inhibitors of PAI-1 arrest this serpin in its active form instead of increasing the speed of conversion. Using docking calculations, we located two possible binding sites for these chemicals. The sites are in proximity of the P1/P1' amino acids of the RCL of PAI-1. Binding in this area can inactivate PAI-1 and additionally create a steric obstacle on the RCL making insertion of this loop between the A3 and A5 strands more difficult; hence abolishing a necessary step in the conversion of this protein into the latent form. Additionally, PAI-1 inhibitors link the RCL of one PAI-1 molecule with the strand 3C and strand 4C or helix A and strand 1B regions of the other PAI-1 molecule aiding polymerization or stabilizing the junction of the two. The polymerization of PAI-1 reduces PAI-1 activity by encapsulating the critical RCL fragment inside the formed PAI-1/PAI-1 polymers.