The purification from rat liver of a nuclease hydrolysing ribonucleic acid and deoxyribonucleic acid

Abstract

The purification of a nuclease from rat-liver mitochondria is described. The mitochondria are rendered soluble by treatment with Triton X-100 and, after fractionation with ammonium sulfate and acetone, the active fraction is further purified by chromatography on diethylaminoethyl-cellulose and Sephadex G-75 to give a purification of over 700-fold. The purified enzyme was only very slightly contaminated with deoxyribonuclease n, phosphodiesterase and phospho-monoesterase. The individual activities of these enzymes did not exceed 0.1% of the activity of the liver nuclease. The purified enzyme attacked ribonucleic acid (RNA) more rapidly than denatured deoxyribonucleic acid (DNA) and hydrolyzed native DNA more slowly than denatured DNA. There is some evidence to suggest that the nucleolytic activity of the purified preparation towards native DNA, denatured DNA and RNA is associated with a single protein. The enzyme is relatively labile but is stabilized in the presence of 20% (w/v) glycerol or 10mM 2-mercaptoethanol.