[Biospecific chromatography of poly(A)-containing RNA on poly(U)-Sepharose]

It is shown that in addition to specific binding of polyadenylic sequence with poly(U), the chromatography of poly(A)-containing RNAs on poly(U)-Sepharose is accompanied by nonspecific irreversible adsorption of polynucleotides on Sepharose gel. This disadvantage may be overcome by establishing optimal BrCN/Sepharose rations during Sepharose activation and by many-fold treatment of poly(U)-Sepharose with ethanolamine immediately before chromatography of RNAs. It was also found that the efficient separation of poly(A+)-RNA preparations from poly(A-)-RNAs is achieved only after double chromatography of RNA on poly(U)-Sepharose. The amount of poly(A+)-RNA in total RNA preparations isolated from bound polyribosomes of 10-day-old chick embryos is equal to 1%. Data from PAAG gel electrophoresis are indicative of the lack of degradation and high heterogeneity of the preparations under study.