PURIFICATION AND CHARACTERIZATION OF A NOVEL POLY(U), POLY(C) RIBONUCLEASE FROM SACCHAROMYCES-CEREVISIAE

A new ribonuclease from Saccharomyces cerevisiae, specific for poly(U) and poly(C) substrate, was purified near to homogeneity by successive fractionation with DEAE-Sepharose, Heparin-Sepharose and CM-Sepharose chromatography. The purified molecule detected by SDS/polyacrylimide gel electrophoresis has a molecular mass of 29 kDa. The optimum PH for the enzyme activity is 5.5-7 and its isoelectric point is 7.5. The pu rified enzyme was able to degrade 26S, 18S and 5S rRNAs as well as mRN A obtained from in vitro transcription. No catalytic activity was obse rved when the RNase was incubated with tRNA and double stranded substr ate. Our findings suggest that this novel RNase may play an important role in the processing of RNA in Saccharomyces cerevisiae. (C) 1997 El sevier Science B.V.