A Study of Methylated Polyadenylic Acid.

Copolymers with different contents of adenine and N1-methyl adenine residues have been studied, polyadenylic acid being methylated by sulfate. Thermal stability, circular dichroism and light scattering measurements are in favor of a two-strand structure at neutral pH. Thermal stability of these products is much less sensitive to ionic strength than that of most polynucleotides, and in some cases independent of ionic strength. These copolymers interact or not with poly(U), depending on the percentage of N1-methyl adenine residues. Copolymers with high contents of methyladenine interact with poly(A) at neutral pH. These copolymers do not bind DNA-dependent RNA polymerase. Some results at acid pH are also reported. [ABSTRACT FROM AUTHOR]