中文摘要：

理论和实验研究表明,蛋白质天然拓扑结构对其折叠过程具有重要的影响.采用复杂网络的方法分析蛋白质天然结构的拓扑特征,并探索蛋白质结构特征与折叠速率之间的内在联系.分别构建了蛋白质氨基酸网络、疏水网、亲水网、亲水-疏水网以及相应的长程网络,研究了这些网络的匹配系数（assortativity coefficient）和聚集系数（clustering coefficient）的统计特性.结果表明,除了亲水-疏水网,上述各网络的匹配系数均为正值,并且氨基酸网和疏水网的匹配系数与折叠速率表现出明显的线性正相关,揭示了疏水残基间相互作用的协同性有助于蛋白质的快速折叠.同时,研究发现疏水网的聚集系数与折叠速率有明显的线性负相关关系,这表明疏水残基间三角结构（triangle construction）的形成不利于蛋白质快速折叠.还进一步构建了相应的长程网络,发现序列上间距较远的残基接触对的形成将使蛋白质折叠进程变慢.

英文摘要：

The theoretical and experimental studies have showed that the topology of the native structure of protein plays an important role in determining its folding process. The complex network approach was used to analyze the topological characters of the native structure of protein and then explore the relationship between these characters and the experimental folding rates. Several types of network were constructed, including all-amino-acids network, hydrophobic amino acid network, hydrophilic amino acid, hydrophobic-hydrophilic amino acid network and their corresponding long-range interaction network. The statistic characters of the assortativity coefficient and the clustering coefficient were studied. The results indicate that all types of network except for the hydrophobic-hydrophilic one are of the positive assortativity coefficient. Furthermore, there is an obvious linear positive correlation between the assortativity coefficient and the folding rate for the all amino acids network and the hydrophobic amino acid network, which implies that the cooperative interactions of the hydrophobic amino acids are important for proteins rapidly folding into their native states. Moreover, it is found that there is a clear linear negative correlation between the clustering coefficient of the hydrophobic amino acid networks and the experimental folding rates of the corresponding proteins, which indicates that the formation of the triangle construction among the amino acids reduces the folding rates. It is also found that in the long-range interaction networks, the formation of contact pairs linking two distant residues in sequence would slow down the process of protein folding.