LOCALIZATION OF N6-(DELTA2-ISOPENTENYL)ADENOSINE AMONG ACCEPTOR SPECIES OF TRANSFER RIBONUCLEIC ACID OF LACTOBACILLUS ACIDOPHILUS

Growth of Lactobacillus acidophilus in medium containing radioactive mevalonic acid results in the incorporation of radioactivity into those species of transfer ribonucleic acid containing N6-(Δ2-isopentenyl)adenosine. Fractionation studies on such labeled transfer ribonucleic acid by two procedures indicates that the unusual nucleotide is localized only in transfer ribonucleic acid molecules that accept leucine, tyrosine, cysteine, serine, and tryptophan. However, not all the subspecies of the transfer ribonucleic acid for leu-diethylaminoethylcine and serine contain N6-(Δ2-isopentenyl)adenosine. N6-(Δ2-Isopentenyl)adenosine could not be demonstrated in the transfer ribonucleic acid chains for aspartic and glutamic acids, arginine, histidine, lysine, glycine, alanine, threonine, valine, proline, and phenylalanine. The observed distribution of N6-(Δ2-isopentenyl)adenosine is consistent with the model that a transfer ribonucleic acid must have an anticodon whose 3′ end is the base A in order to contain N6-(Δ2-isopentenyl)- adenosine in the adjacent position. © 1969, American Chemical Society. All rights reserved.