Base Sequence at the 5'-Linked Terminus of Tobacco Mosaic Virus Ribonucleic Acid

The 5'-hydroxyl-linked end of tobacco mosaic virus ribonucleic acid has been labeled with semicarbazide-14C, and the modified ribonucleic acid has been hydrolyzed with T1 ribonuclease. The end fragment, bearing the label, was isolated by two chromatographic procedures, which indicated that the oligomer was a tetramer containing only adenine and cytosine. In separate experiments, a similar end fragment has been isolated from the hydrolysis products of unaltered tobacco mosaic virus ribonucleic acid. The optical rotatory dispersion and absorption spectra of this oligomer have been measured at three pH values. In addition, the products of a spleen phosphodiesterase digest have been identified and estimated. The data support the designation of GpCpCpCpA as the terminal sequence.