Osmium-labeled polynucleotides: reaction of osmium tetraoxide, with poly-1,N6-ethenoadenylic acid

Abstract

Osmium tetraoxide, in the presence of ligands such as pyridine and bipyridine, adds across the etheno bridge of 1,N6-etheno-9-methyladenine and poly-1,N6-ethenoadenylic acid. The Os:P ratio in the labeled polynucleotide was approximately equal to 1 when bipyridine was used as the stabilizing ligand. A similar study with polycytidylic acid, which had been partially modified with chloroacetaldehyde so that some bases were converted to 3,N4-ethenocytosine, gave an OS:P ratio of approximately equal to 1.3. Calf-thymus DNA, in which the adenine and cytosine bases were modified by chloroacetaldehyde, gave an Os:P ratio of approximately equal to 1 after 24 h. These results suggest that 3,N4-ethenocytosine will add two Os labels.