RNase I degrades single-stranded RNA to nucleoside 3´ monophosphates via 2´,3´ cyclic monophosphate intermediates by cleaving between all dinucleotide pairs, ^2,3 unlike RNase A, which cleaves only after cytosine and uridine. In addition, the enzyme is completely inactivated by heating at 70 °C for 15 minutes, eliminating the requirement to remove the enzyme prior to many subsequent procedures.

Applications

• Removal of RNA from DNA preparations. ¹
• RNase protection assays to detect single-base pair mismatches in RNA:RNA and RNA:DNA hybrids. ¹

Figure 1. Removal of RNA from plasmid DNA preparations. Plasmid DNA was prepared from 1.5 mL of an overnight culture, suspended in 50 µL TE buffer (10 mM Tris-HCl (pH 8), 1 mM EDTA), and treated with RNase A, RNase I, or no enzyme. Five µL of each reaction were resolved by agarose gel electrophoresis and visualised by staining with ethidium bromide. Lane 1, no RNase; Lane 2, 1.5 U of RNase I; Lane 3, 20 µg/mL RNase A; MW, 1-kb ladder. Arrow denotes small undigested RNA.

References

1. Johnson, M. (1996) Epicentre Forum 3(4), 7.
2. Shen, V. and Schlessinger, D. (1982) The Enzymes XV (Part B), 501.
3. delCardayré, S.B. and Raines, R.T. (1995) Anal. Biochem. 225, 176.