Half-life of tRNA Containing N6(Δ2-isopentenyl)adenosine in Lactobacillus acidophilus ATCC 4963

tRNA containing N⁶-(Δ²-isopentenyl)adenosine may be precursors for the plant hormone cytokinin. To discriminate between tRNA containing and not containing cytokinin nucleotides, double labelling experiments were made by the use of 2¹⁴C]-mevalonic acid and ³H-methyl]-methionine. At a generation cycle of 2 h for Lactobacillus acidophilus ATCC 4963, the half-lives of tRNA labelled with ³H-methyl]-methionine and 2-¹⁴C]-mevalonic acid are similar, namely 3 h. Isopentenylation of tRNA could be measured to be maximally 1:10.