Bovine Pancreatic RNAase Research Articles

Studies on cellular inhibitors of ribonuclease II. Some properties of the inhibitor from rat liver

Both the rat-liver RNAase inhibitor and heparin inhibited bovine pancreatic RNAase (at pH 7.8 and 5.8), but did not affect the activity of RNAase T 1 , an alkaline enzyme of fungal origin, or of several acid RNAases derived from plant tissue. These inhibitors differed in their activity towards the enzymes from rat liver. The acid RNAase was inhibited by heparin, but not by the rat-liver inhibitor. The two alkaline RNAase preparations were inhibited by the rat-liver inhibitor, but only slightly affected by heparin. The purified rat-liver inhibitor was inactivated by low concentrations of papain (of several enzymes tested), periodate, sulfhydryl reactants and protamine, and by high salt concentrations. Inactivation by PCMB and Pb 2+ was partially reversible. Inhibition of RNAase activity by heparin was more sensitive to protamine and to salt concentration than was inhibition by the rat-liver inhibitor. These results indicate the protein nature of the rat-liver inhibitor, but suggest carbohydrate may also be an essential component. The rat-liver inhibitor may be classed as a polyanionic inhibitor, but one which forms a comparatively strong complex with RNAase.