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The ribonuclease enzyme system in rat brain Popow, William Philip


A study was made of the enzyme system responsible for the catabolism of ribonucleic acid in rat brain. Initial work with whole brain homogenates and extracts revealed the presence of three ribonucleases (RNases) distinguishable by the pH at which they exhibit optimal activity. The identified RNases are referred to according to their pH optima as pH 6.7 RNase, pH 7.8 RNase and pH 9.5 RNase. Evidence was also obtained indicating the presence of a protein inhibitor of the pH 7.8 RNase. The components of this multi-enzyme-inhibitor system were separated and partially purified by ammonium sulphate fractionation of whole brain extracts followed by DEAE-cellulose column chromatography of the ammonium sulphate precipitable fractions. The DEAE-cellulose eluate RNases were characterized with regard to the effect of various reagents upon their activity. The intracellular distribution and developmental profiles of the three RNase activities and the pH 7.8 RNase inhibitor activity were also determined.

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