Affinity chromatography of poly(adenylic acid)-containing ribonucleoproteins on oligothymidylic acid-cellulose

Binding of poly(A)-containing RNP to oligo(dT)-cellulose has been investigated as a function of mono- and divalent ion concentration. 80-90% binding was obtained either in high (500 mM) or in moderate NaCl concentrations in the presence of 5 mM MgCl2. At 40 mM NaCl and 5 mM MgCl2 poly(A)+-RNP exhibit approximately the same stability as poly(A)+-RNA in binding to oligo(dT)-cellulose with a melting temperature of 41 and 45 degrees C, respectively, indicating that the protein moiety has no effect on the ribonucleoprotein binding in these conditions. Differences were observed in the elution of poly(A)+-RNA and poly(A)+-RNP from oligo(dT)-cellulose in buffer without salts. Poly(A)+-RNA was completely removed at 4 degrees C whereas the melting temperature of poly(A)+-RNP was only decreased to 34 degrees C. The isolation of poly(A)+-RNP by thermal elution from oligo(dT)-cellulose is described.