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Updated: Sep 18, 2026
Overexpressing and Purifying a Toxic Nuclease from Escherichia coli
Published on: August 29, 2025
Improvement of the Purification Process for Earthworm DNase and Cytotoxicity Analysis
Zhiqiang Zhu1, Xiuwei Wang2, Zhen Gua2
1Translational Medicine Research Laboratory, Capital Institute of Pediatrics (Capital Center for Children's Health, Capital Medical University), 327 Room, 3Rd Floor, Research Building, 2 Yabao Road, Chaoyang District, Beijing, 100020, China. zzhq8888@126.com.
Objectives:
Deoxyribonuclease (DNase) is widely used in treating obstructed purulent sputum drainage caused by bronchiectasis, lung abscess, cystic fibrosis, and atelectasis and inhibits biofilm formation.
Methods:
This study optimized the earthworm DNase extraction process. Tissue homogenates were prepared using mechanical homogenization, followed by isoelectric precipitation and acetone precipitation. Crude earthworm extracts (EWE) were purified by ion exchange chromatography. DNase activity was evaluated by Bradford assay and UV absorption method.
Results:
Method 1 took 42-45 h, while method 2 took 15-18 h. The specific activity of EWE1 was 677.48 ± 52.84 U/mg. The specific activity of EWE2 was 622.03 ± 49.76 U/mg. Following weak cation exchange chromatography and heparin affinity chromatography, the enzyme activity of the extract was 4443.33 ± 266.59 U/mg. The minimum working concentration was 1.88 µg/mL.
Conclusion:
The improved extraction process markedly reduced the preparation time and enhanced DNase specific activity of earthworm extract.
