Can someone plz tell me that why DNAase chop down RNA as well DNA because it specificity is only for DNA?

I have treated many time my RNA sample which was DNA contaminated when I used DNA 4 U for 5ug RNA then it also chop down my RNA sample when i use 0.2 U for 5 ug RNA then RNA was clear two bands 

06 July 2015 9,195 3 View