A single site mutation significantly improves the thermostability and activity of heparinase I from Bacteroides eggerthii

摘要

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.