Gradient partition chromatography of transfer ribonucleic acid from Escherichia coli, strain B, reveals 56 transfer ribonucleic acid chains for 20 amino acids. Acceptor profiles, determined with partially purified aminoacyl transfer ribonucleic acid synthetases, demonstrate three transfer ribonucleic acids for asparagine, cysteine, glycine, histidine, and threonine; four transfer ribonucleic acids for proline, and five transfer ribonucleic acids for tryptophan. Each of the tryptophan transfer ribonucleic acid can exist in an active and an inactive conformation as measured by response to chloroquine in the charging medium. Although asparagine transfer ribonucleic acids and aspartic acid transfer ribonucleic acid emerge in the same region of the profile, asparagine and aspartic acid do not share common acceptors, as shown by studies involving periodate oxidation. The profiles of leucine and tyrosine acceptor are essentially constant for different lots of transfer ribonucleic acid prepared from commercial cells, whereas the acceptor profiles for eight other amino acids vary markedly. The variability is not explainable by differential extraction or artifacts in resolution.
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