Ribonuclease activity in preparations of human leukocytic interferon

A ribonuclease (RNase) with pH optimum at 7.0–7.5 was found after multistage chemical purification of preparations of human leukocytic interferon. The enzyme had an endonuclease mechanism of action. Analysis of the results of a study of the action of various substances on the RNase activity of human interferon preparations showed that many of them acted on the enzyme in the same way as on other ribonucleases. However, unlike the inactivating action on pancreatic RNase, interferon RNase was activated by dithiothreitol, a reducing agent for disulfide groups. During electrophoresis in polyacrylamide gel distribution patterns of protein and RNase were obtained.