Detection of Uridine 3-Ethyl Phosphate and Homologues in Digests of Ribonucleic Acid Hydrolyzed with Pancreatic Ribonuclease in the Presence of Traces of Ethanol

32P-labeled ribonucleic acid of the bacteriophage MS2 was digested with pancreatic ribonuclease to a mixture of oligonucleotides of the general formula (Purine nucleotide)n Pyrimidine nucleotide. In addition to the oligonucleotides, and to a small amount of uridine 2″, 3″-cyclic phosphate resulting from incomplete enzyme action, three minor componcnts were detected. They were identified as uridine 3″-ethyl phosphate, adenylyl (3″, 5″)-uridine 3″-ethyl phosphate and guanylyl-(3″, 5″)- uridine 3″-ethyl phosphate. Identification was based on enzymic and chemical hydrolysis and on analysis by gas chromatography of the hydrolysate. These ethyl esters were not components of the viral ribonucleic acid, but, werc synthesized enzymically from traces of ethanol present in the digests and originating from the ethanol precipitation of the ribonucleic acid.