Purification and properties of two ribonucleases and a nuclease from barley seeds

Three enzymes possessing RNAase activity were isolated from barley seeds. These enzymes were further purified by ammonium sulphate precipitation DEAE-cellulose chromatography, gel filtration on Sephadex G-75 and DEAE-Sephadex A-50 chromatography. These enzymes have been characterized and classified as: 1. Plant RNAase I (EC 3.1.27.1). It has a pH optimum at 5.7 and molecular weight of 19 000. 2. Plant RNAase II (EC 3.1.27.1). It has a pH optimum at 6.35 and molecular weight of 19 000. 3. Plant nuclease I (EC 3.1.30.2). It has a pH optimum at 6.8 and molecular weight of 37 000. Two RNAases were purified to homogeneity by means of affinity chromatography on poly(G)-Sepharose 4B, as shown by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate.