Abstract

The applications of heparinase I in the preparation of low molecular weight heparin were limited due to the poor thermostability. In this work, the Foldx was used to calculate the folding free energy to find the possible thermal stable conformation. In the calculation results, the mutant Q157H had the lowest folding free energy in 17 possible mutants indicating that the Q157H was more stable than the wild-type heparinase I. The mutant Q157H exhibited a 6.0-fold and 2.1-fold half-life time than that of the wild type (WT). Notably, the enzyme activity of Q157H was also increased 1.88-fold compared with the WT. To explore the role of the mutation Q157H on the structure of heparinase I, molecular dynamic (MD) simulation and docking were performed. The MD simulation revealed that the Q157H had lower root-mean-square deviation (RMSD) value than the WT. Moreover, the model showed 11 hydrogen bonds formed between the mutant with the heparin, and there were 4 more hydrogen bonds than that of the WT. Based on the molecule docking results, the Q157H had a higher affinity than the WT. This work will expand the applications of heparinase in the industry and clinic.

摘要

由于热稳定性差，肝素酶Ⅰ在制备低分子肝素方面的应用受到限制。在这项工作中，Foldx 用于计算折叠自由能，以找到可能的热稳定构象。在计算结果中，突变体 Q157H 在 17 个可能的突变体中具有最低的折叠自由能，表明 Q157H 比野生型肝素酶 I 更稳定。突变体 Q157H 的半衰期比野生型肝素酶 I 高 6.0 倍和 2.1 倍。野生型（WT）。值得注意的是，与 WT 相比，Q157H 的酶活性也增加了 1.88 倍。为了探索突变Q157H对肝素酶I结构的作用，进行了分子动力学（MD）模拟和对接。MD 模拟显示，Q157H 的均方根偏差 (RMSD) 值低于 WT。此外，该模型显示突变体与肝素之间形成了11个氢键，比WT多4个氢键。根据分子对接结果，Q157H 的亲和力高于 WT。这项工作将扩大肝素酶在工业和临床中的应用。