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Biochem Biophys Res Commun. 2011 Apr 1;407(1):113-7. doi: 10.1016/j.bbrc.2011.02.120. Epub 2011 Mar 21.

An enzyme from the earthworm Eisenia fetida is not only a protease but also a deoxyribonuclease.

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State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, 15 Da Tun Road, Chao Yang District, Beijing 100101, China.


The earthworm enzyme Eisenia fetida Protease-III-1 (EfP-III-1) is known as a trypsin-like protease which is localized in the alimentary canal of the earthworm. Here, we show that EfP-III-1 also acts as a novel deoxyribonuclease. Unlike most DNases, this earthworm enzyme recognizes 5'-phosphate dsDNA (5'P DNA) and degrades it without sequence specificity, but does not recognize 5'OH DNA. As is the case for most DNases, Mg(2+) was observed to markedly enhance the DNase activity of EfP-III-1. Whether the earthworm enzyme functioned as a DNase or as a protease depended on the pH values of the enzyme solution. The protein acted as a protease under alkaline conditions whereas it exhibited DNase activity under acid conditions. At pH 7.0, the enzyme could work as either a DNase or a protease. Given the complex living environment of the earthworm, this dual function of EfP-III-1 may play an important role in the alimentary digestion of the earthworm.

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