BIOSYNTHESIS OF N6-(DELTA2-ISOPENTENYL)ADENOSINE . PRECURSOR RELATIONSHIP OF ACETATE AND MEVALONATE TO DELTA2-ISOPENTENYL GROUP OF TRANSFER RIBONUCLEIC ADID OF MICROORGANISMS

The Δ2-isopentenyl group occurs in the transfer ribonucleic acid (tRNA) of yeast, mammalian tissue, and plant tissue as N6-(Δ2-isopentenyl)adenosine (IPA). This group represents the basic building block for the synthesis of isoprenoid compounds. The question was asked whether this Δ2-isopentenyl side chain originates from the pool of isoprene units in the cell. When Baker’s yeast was grown in the presence of [2-14C]acetate, the tRNA became labeled and 3% of this activity was located in the Δ2-isopentenyl group of the IPA. When the mevalonate-requiring organisms, Lactobacillus acidophilus and Lactobacillus plantarum, were grown in the presence of [2-14C]mevalonate, the tRNA became labeled and all the radioactivity could be accounted for in the side chain of the IPA. Under the present experimental conditions, mevalonate was not incorporated into the tRNA of yeast. © 1968, American Chemical Society. All rights reserved.