PURIFICATION OF ESCHERICHIA COLI PULSE-LABELED RNA BY BENZOYLATED DEAE-CELLULOSE CHROMATOGRAPHY

The rapidly-labeled RNA fraction of Escherichia coli has been purified approximately 15-fold on benzoylated DEAE-cellulose columns. It is metabolically unstable (as shown by a pulse/chase experiment), and is considered to represent messenger RNA. The yield of pulse-labeled RNA is about 70% and comprises 4 to 5% of the RNA of the cell. The true size distribution of this RNA, determined by sedimentation in a denaturing solvent (99% dimethyl sulfoxide), does not change during purification. This result indicates that neither degradation nor selection for molecules of a particular size has occurred. Upon sedimentation of the final preparation in dimethyl sulfoxide, the distribution of pulse label is the same as that of RNA mass, indicating nearly complete separation from longer-lived RNA components. © 1969.