STUDIES ON 5-FLUOROURACIL-CONTAINING RIBONUCLEIC ACID .I. SEPARATION AND PARTIAL CHARACTERIZATION OF FLUOROURACIL-CONTAINING TRANSFER RIBONUCLEIC ACIDS FROM ESCHERICHIA COLI

Transfer ribonucleic acid isolated from Escherichia coli B grown in the presence of 5-fluorouracil consists of a mixture of normal and 5-fluorouracil- containing transfer ribonucleic acids. This mixture may be resolved into the normal and 5-fluorouracilcontaining components by DEAE-cellulose column chromatography in the presence of 0.02 M Tris-HCl (pH 8.9) and a concave upward NaCl gradient. Recovered normal and 5-fluorouracil-containing transfer ribonucleic acids, having from 80 to 84% of the uracil residues replaced by 5-fluorouracil, are still about 90% active in their ability to accept amino acids. Only seven amino acids (Arg, Asn, Gln, His, Pro, Thr, and Val) were accepted by both transfer ribonucleic acid species to the same extent, however. Norma transfer ribonucleic acids accepted seven amino acids (Ala, Glu, Gly, Ile, Leu, Met, and Ser) to a greater extent and six (Asp, Cys, Lys, Phe, Trp, and Tyr) to a lesser extent than did 5-fluorouracil-containing transfer ribonucleic acids. The ultraviolet absorption spectra of the 5-fluorouracil-containing transfer ribonucleic acids is shifted slightly toward the longer wavelengths when compared with normal, but the ε(P) values are essentially the same. This procedure permits the separation of relatively large amounts of material and should lend itself to further scaling up. Recoveries were generally around 90%. © 1969, American Chemical Society. All rights reserved.