[Polysome ribonucleases of leukemic cells]

The composition of ribosomal proteins isolated from normal homopoietic and leucemic cells was studied by analytic electrophoresis in polyacrylamide gel. It was found that acid-soluble proteins from polysomal complexes can be separated into 21-22 components in the acid system. There was no significant differences in protein components from normal and leucemic polysomes by their quantity and mobility in polyacrylamide gel. Five protein components possess a ribonuclease activity as it was established by using technique of direct RNase assay in electrophoregrams. All ribonuclease-active components have pH optimum at 7.6-7.8. No differences were detected in the number and activity of particular enzyme components of polysomes isolated from normal hemopoietic and leucemic tissues. It is suggested that the number and presence of RNases in polysome complexes is likely to play not a significant role in regulation of polysome activity, but influence of inhibitors makes this supposition possible.