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

Abstract

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 MgCl 2. At 40 mM NaCl and 5 mM MgCl 2 poly(A) +-RNP exhibit approximately t he same stability as poly(A) +-RNA in binding to oligo(dT)-cellulose with a melting temperature of 41 and 45°C, respectively, indicating that the protein moeity has no effect on the ribonucleoprotein binding in these conditions. Differences were observed int he 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°C whereas the melting temperature of poly(A) +-RNP was only decreased to 34°C. The isolation of poly(A) +-RNP by thermal elution from oligo(dT)-cellulose is described.