Molecular insight into the steric shielding effect of PEG on the conjugated staphylokinase: biochemical characterization and molecular dynamics simulation.
Molecular insight into the steric shielding effect of PEG on the conjugated staphylokinase: biochemical characterization and molecular dynamics simulation.
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PEG 对缀合葡萄球菌激酶的空间屏蔽效应的分子洞察：生化表征和分子动力学模拟
DOI：
10.1371/journal.pone.0068559
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Yu J
中科院分区：
文献类型：
--
作者：
Mu Q;Hu T;Yu J
聚乙二醇化是提高治疗性蛋白质效力的成功方法。提高的治疗效力主要是由于PEG的空间屏蔽效应。然而，这种作用对蛋白质的潜在机制还不清楚，特别是蛋白质与其高分子量底物或受体的相互作用。在这里，实验研究和分子动力学模拟被用来提供分子洞察PEG化蛋白质和它的受体之间的相互作用。葡激酶（Sak），一种用于冠状动脉血栓溶解的治疗性蛋白质，被用作模型蛋白质。通过将5 kDa/20 kDa PEG分别与Sak的N-末端和C-末端位点特异性缀合来制备四种PEG化的Sak。实验研究表明，Sak的天然构象基本上不被PEG化改变。相比之下，PEG化的Sak的生物活性、流体动力学体积和分子对称形状被改变并且依赖于PEG链长度和PEG化位点。PEG化Saks的分子建模表明PEG链保持高度柔性，并且可以形成独特的水合层，从而导致PEG的空间屏蔽效应。对接分析表明，Sak与其受体的结合亲和力依赖于PEG链长度和PEG化位点。计算模拟结果很好地解释了实验数据。我们的研究阐明了蛋白质表面PEG链的分子细节，可能对PEG化蛋白质的合理设计、制备和临床应用至关重要。
PEGylation is a successful approach to improve potency of a therapeutic protein. The improved therapeutic potency is mainly due to the steric shielding effect of PEG. However, the underlying mechanism of this effect on the protein is not well understood, especially on the protein interaction with its high molecular weight substrate or receptor. Here, experimental study and molecular dynamics simulation were used to provide molecular insight into the interaction between the PEGylated protein and its receptor. Staphylokinase (Sak), a therapeutic protein for coronary thrombolysis, was used as a model protein. Four PEGylated Saks were prepared by site-specific conjugation of 5 kDa/20 kDa PEG to N-terminus and C-terminus of Sak, respectively. Experimental study suggests that the native conformation of Sak is essentially not altered by PEGylation. In contrast, the bioactivity, the hydrodynamic volume and the molecular symmetric shape of the PEGylated Sak are altered and dependent on the PEG chain length and the PEGylation site. Molecular modeling of the PEGylated Saks suggests that the PEG chain remains highly flexible and can form a distinctive hydrated layer, thereby resulting in the steric shielding effect of PEG. Docking analyses indicate that the binding affinity of Sak to its receptor is dependent on the PEG chain length and the PEGylation site. Computational simulation results explain experimental data well. Our present study clarifies molecular details of PEG chain on protein surface and may be essential to the rational design, fabrication and clinical application of PEGylated proteins.
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