Pyrophosphate in the 5' terminal position of a viral ribonucleic acid.

A pancreatic ribonuclease digest of carbon-14-labeled Satellite Tobacco Necrosis Virus RNA was fractionated, according to charge, by column chromatography. Individual fractions were dephosphorylated with alkaline phosphomonoesterase and rechromatogramed. The fraction originally containing oligonucleotides with seven negative charges separated into two components corresponding to five and two negative charges, respectively, and therefore must have contained a terminal trinucleotide 5'-pyrophosphate, in addition to the internal hexanucleotides. Other fractions when similarly treated were found to contain only internal oligonucleotides.