Purification and Properties of Ribonuclease From Buffalo Milk Whey

A procedure was developed for isolation and identification of ribonuclease from buffalo milk whey. Ribonuclease was precipitated with (NH₄)₂SO₄ between 65 and 90% saturation. The precipitate was dissolved, dialyzed, and fractionated on DEAE-cellulose. Two ribonuclease-rich fractions were collected, i.e. ribonuclease A and B. Ribonuclease A had an optimum pH of 7 .0, and ribonuclease B had an optimum pH of 8.6. Both had an optimum temperature at 38 C. The ribonucleases in the purified state were unstable to heat and their activity decreased as the time of exposure increased. Both enzyme fractions were sensitive to inhibitors. NaCl and NaN₃ were stimulatory for ribonuclease A, while ribonuclease B was stimulated only by NaCl.