title: An enzyme from the earthworm Eisenia fetida is not only a protease but also a deoxyribonuclease.
abstract: 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.
authors.affiliation: State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, 15 Da Tun Road, Chao Yang District, Beijing 100101, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Pan
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Hai-Jin
authors.initials: HJ
authors.lastname: He
authors.forename: Rong-Qiao
authors.initials: RQ
authors.lastname: He
mesh_terms: D000818:Animals; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D009835:Oligochaeta / Q000201:enzymology*; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000302:isolation & purification; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D012964:Sodium / Q000737:chemistry; D013696:Temperature
chemical_list: D015842:Serine Proteinase Inhibitors; C114880:trypsin-like serine protease; D012964:Sodium; D003851:Deoxyribonucleases; D012697:Serine Endopeptidases; D008274:Magnesium