STUDIES ON ESCHERICHIA COLI METHIONINE TRANSFER RIBONUCLEIC ACIDS

We have devised a simplified method for the purification of the bacterial initiator tRNA, tRNAfMet in amounts greater than 100 mg from 10 g of unfractionated tRNA. The purification of the normal methionine tRNA, tRNAmMet, was also achieved but with a lower yield. During the fractionation studies we identified two chromatographically separable species of tRNAfMet and two of tRNAmMet. The triplet binding assay did not differentiate between fMet‐tRNAf1 and fMet‐tRNAf2 or between Met‐tRNAm1 and Met‐tRNAm2. An anticodon containing fragment of tRNAmMet did not inhibit the charging of tRNAfMet or of tRNAmMet under conditions where it should behave as a linear sequence of nucleotides. Both tRNAfMet and tRNAmMet contain approximately one mole of the minor nucleoside, 4‐thiouridine, per mole of tRNA. In our functional tests the presence of 4‐thiouridine was not necessary for the biological activity of tRNAfMet. Copyright © 1969, Wiley Blackwell. All rights reserved