The Primary Structure of Valine-I Transfer Ribonucleic Acid from Torulopsis utilis

Abstract

Highly purified tRNA₁^val from Torulopsis utilis, prepared by chromatography on DEAE-Sephadex columns, has been completely digested with pancreatic RNase [EC 2.7.7.16] and with RNase T1 [EC 2.7.7.26]. The separation and identification of the products have been carried out mainly by column chromatography. Analyses indicate that this RNA is composed of 75 nucleotide residues including 12 unusual nucleo-tides. This RNA contains common sequence G-T-Ψ-G- in all tRNA's of known structure, A-G-hU- common to yeast tRNA's and a probable anticodon for valine, I-A-Gp. Several long sequences have been established by overlapping of the fragments obtained from the two digests. The nucleoside adjacent to the 3'-side of the probable anticodon in this RNA has been found to be adenosine itself, while this position in most of the tRNA's of known structure is occupied by unusual nucleosides. The primary structure of this RNA has been determined after partial digestion with RNase T1, as stated in the subsequent paper.