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Updated: Jun 28, 2026
Overexpressing and Purifying a Toxic Nuclease from Escherichia coli
Published on: August 29, 2025
Purification and characterization of deoxyribonuclease from earthworm Eisenia foetida
Jian-lin Zhang1, Zhi-zhen Liu, Xiao-yuan Wang
1Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan 030001, China.
Objective:
To purify a kind of deoxyribonuclease from earthworm Eisenia foetida (named earthworm DNase, EDNase) and study its characteristics.
Methods:
Acetone precipitation, ion-exchange chromatography, high performance liquid chromatography, SDS-PAGE, Capillary electrophoresis isoelectric focusing and MALDI-TOP MS were used for the study.
Results:
This purified protocol improved 137-fold purification and 45.6% recovery of enzyme activity. The molecular mass of EDNase was estimated to be 63,000. Mg2+, Mn2+ and Ca2+ were strong inhibitors of EDNase, while Na+ slightly increased the enzyme activity. The enzyme was completely stable in the pH range from 4.4 to 5.2 and had a pH optimum of 4.8. The optimum temperature was 37 degree C and the enzyme was stable up to 40 degree C. The pI of the enzyme was 6.20. Km and Vmax for the enzyme were 1.52 g/L and 4.89 mg/(mL.min), respectively, with calf thymus DNA as substrate. The enzyme was able to degrade chromosomal DNA, linear lambda-bacteriophage DNA as well as supercoiled plasmid DNA, but didn't display any RNase activity.
Conclusion:
This kind of deoxyribonuclease possesses unique characteristics, which is different from the deoxyribonucleases which we have known before.
