Figure 6.

Ribonucleolytic activity of the recombinant protein. (A) Standard amounts (50 µg) of poly(C) (solid diamonds), poly(U) (solid triangles) and rRNA (open squares) were incubated at 37°C for 3 h with different amounts of purified recombinant Cc RNase as described in Materials and Methods. The reaction was stopped by addition of perchloric acid containing uranyl acetate and acid-soluble ribonucleotides remaining in the supernatant fraction after centrifugation were quantitated spectrophotometrically at 260 nm. Error bars represent means ± SE (n = 3). (B) An aliquot of 2 µg of rRNA from rat liver was incubated with 0.4 µg of purified recombinant Cc RNase at 37°C for 5 (lane 2), 10 (lane 3) and 15 min (lane 4). An equal amount of rRNA without Cc RNase was also incubated at 37°C for 15 min (lane 1). The reaction products were analyzed by 1% agarose gel electrophoresis and visualized with ethidium bromide staining. Arrows show 28S and 18S rat rRNA.