Chemical characterization of tobacco necrosis and satellite viruses

Tobacco necrosis virus (AC36TNV) and satellite virus (SV-C) were compared as to amino acid composition and nucleotide ratio. The numbers of amino acid residues (not including tryptophan) per subunit and subunit molecular weights, determined by amino acid analysis and tryptic peptide chromatography, were 209 and 24,900 for SV-C, and 197 and 22,600 for AC36TNV. Neither virus has a free N-terminal residue. The C-terminal residue was leucine for SV-C, and isoleucine for AC36TNV. Molar percentages in both viruses were similar for cytosine and uracil, and somewhat different for adenine and guanine. s 20,w values for the viral RNA's were 14.2 ± 2 for SV-C, and 24.1 ± 2 for AC36TNV. The extinction coefficient at 260 mμ was 5.3 mg/cm 2 for SV-C, and 5.0 mg/cm 2 for AC36TNV.