In vitro evolution methods are often used to modify protein with improved characteristics. We developed a directed evolution protocol to enhance the thermostability of the beta-1,3-1,4-glucanase. The thermostability of the enzyme was significantly improved after two rounds of directed evolution. Three variants with higher thermostability were obtained. The mutant enzymes were further analyzed by their melting temperature, halftime and kinetic parameters. Comparing to intact enzyme, the T50 of mutant enzymes 2-JF-01, 2-JF-02 and 2-JF-03 were increased by 2.2 degrees C, 5.5 degrees C and 3.5 degrees C, respectively, the halftime (t1/2, 60 degrees C) of mutant enzymes 2-JF-01, 2-JF-02 and 2-JF-03 were shortened by 4,13 and 17 min, respectively, the V(max) of mutant enzymes were decreased by 8.3%, 2.6% and 10.6%, respectively, while K(m) of mutant enzymes were nearly unchanged. Sequence analysis revealed seven single amino acid mutant happened among three mutant enzymes, such as 2-JF-01 (N36S, G213R), 2-JF-02 (C86R, S115I, N150G) and 2-JF-03 (E156V, K105R). Homology-modeling showed that five of seven substituted amino acids were located on the surface of or in hole of protein. 42.8% of substituted amino acids were arginine, which indicated that arginine may play a role in the improvement of the thermostability of the beta-1,3-1,4-glucanase.This study provide some intresting results of the structural basis of the thermostability of beta-1,3-1,4-glucanase,and provide some new point of view in modifying enzyme for future industrial use.
Amino Acid Sequence ; Bacillus ; enzymology ; Directed Molecular Evolution ; Endo-1,3(4)-beta-Glucanase ; biosynthesis ; chemistry ; genetics ; Enzyme Stability ; Hot Temperature ; Molecular Sequence Data ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; genetics

Objective To evaluate the safety and efficacy of interventional embolization of middle meningeal artery(MMA)for the treatment of chronic subdural hematoma(CSDH).Methods The clinical data of 14 patients with CSDH(17 lesions in total),who were treated with simple embolization of MMA at the Yijishan Hospital of Wannan Medical College of China between July 2021 and July 2022,were retrospective analyzed.After superselective catheterization of MMA using a microcatheter was accomplished,Onyx-18 glue,a liquid embolization agent,was used to embolize the main trunk and the branches of MMA.Imaging follow-up was adopted at 30 days and 90 days after discharge from hospital to evaluate the absorption of hematoma,and the improvement of clinical symptoms was defined as the modified Rankin Scale score(mRS)being decreased≥1 point from the baseline value.Results Successful embolization of MMA was accomplished for all the 17 lesions in the 14 patients,and no procedure-related complications occurred.During the follow-up period,the clinical symptoms and signs were remarkably improved in all patients.The postoperative 90-day hematoma volume was reduced by more than 90%in 11 patients and by more than 40%in one patient,and in 2 patients the postoperative 30-day hematoma volume was reduced by more than 30%.Complete absorption of hematoma was seen in 11 patients,and partial absorption of hematoma was observed in 3 patients.Conclusion For the treatment of newly-developed or recurrent CSDH,interventional embolization of MMA is clinically safe and effective.(J Intervent Radiol,2024,32:12-16)