Purification and properties of double-stranded RNA-degrading nuclease, dsRNase, from the digestive juice of the silkworm, Bombyx mori
2007
Arimatsu, Y.(Kyoto Inst. of Technology (Japan)) | Furuno, T. | Sugimura, Y. | Togoh, M. | Ishihara, R. | Tokizane, M. | Kotani, E. | Hayashi, Y. | Furusawa, T.
A nuclease which degrades double-stranded RNA was purified from the digestive juice of fifth-instar larvae of the silkworm, Bombyx mori, using gel filtration and affinity column chromatography. The enzyme was found to have a molecular weight of 41,000 as estimated by a gel filtration method and detected as a single band with the same molecular weight on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. It degraded double-stranded RNA of cytoplasmic polyhedrosis virus genome, synthetic Poly(I)/Poly(C), Poly(I) and Poly(C). It also digested copolymer Poly(AU), Poly(A) and Poly(U), but showed weak degradation of Poly(A)/Poly(U), Poly(C)/Poly(G), Poly(G) and natural DNA isolated from calf thymus. The pH range wherein the reaction occurred was greater than 7. The purified enzyme did not require Mgsup(2+) to degrade CPV-dsRNA, whereas divalent cations including Mgsup(2+) and Casup(2+) were needed to degrade synthetic Poly(I)/Poly(C). The enzyme activity was suppressed by Cosup(2+), Znsup(2+) and Mnsup(2+).
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