State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, 15 Da Tun Road, Chao Yang District, Beijing 100101, China.
Biochem Biophys Res Commun. 2011 Apr 1;407(1):113-7. doi: 10.1016/j.bbrc.2011.02.120. Epub 2011 Mar 21.
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.
蚯蚓酶 Eisenia fetida 蛋白酶-III-1（EfP-III-1）是一种胰蛋白酶样蛋白酶，定位于蚯蚓的消化道中。在这里，我们表明 EfP-III-1 还具有一种新型的脱氧核糖核酸酶活性。与大多数 DNase 不同，这种蚯蚓酶识别 5'-磷酸化双链 DNA（5'P DNA）并在没有序列特异性的情况下降解它，但不识别 5'OH DNA。与大多数 DNase 一样，观察到 Mg(2+) 明显增强了 EfP-III-1 的 DNase 活性。蚯蚓酶是作为 DNase 还是蛋白酶发挥作用取决于酶溶液的 pH 值。该蛋白在碱性条件下作为蛋白酶发挥作用，而在酸性条件下则表现出 DNase 活性。在 pH 7.0 时，该酶既可以作为 DNase 也可以作为蛋白酶发挥作用。鉴于蚯蚓复杂的生活环境，EfP-III-1 的这种双重功能可能在蚯蚓的消化过程中发挥重要作用。
