RNase A (17500 U)

QIAGEN provides a DNase-free (endonuclease-free) RNase A solution designed for the removal of contaminating RNA during the isolation of plasmid and genomic DNA. The enzyme is an endoribonuclease that breaks down single-stranded RNA molecules by hydrolysis 3' of pyrimidine residues (cytosine and uracil), and it does not hydrolyze DNA because DNA lacks the 2′-OH groups required for forming cyclic intermediates. The protein is composed of 124 amino acids and has a molecular weight of approximately 13.7 kDa.

The preparation is quality-controlled and ready to use in plasmid purification procedures for the digestion of RNA, and is also used to remove contaminating RNA from DNA samples after extraction or PCR when downstream applications such as cloning or sequencing require RNA-free DNA. The enzyme is highly active across a broad range of reaction conditions and is difficult to inactivate; it does not need to be boiled before use. Before use in plasmid and DNA purification, the solution should be centrifuged briefly and added to Buffer P1 to obtain a final working concentration of 100 μg/mL, after which Buffer P1 should be stored at 2–8°C.

The product is supplied at a concentration of 100 mg/mL with an activity of 7000 units/mL. One Kunitz unit is defined as the amount of enzyme causing hydrolysis of RNA at a rate such that the velocity constant (k) equals unity at 25°C and pH 5.0.