Preliminary investigation of tRNA modification enzymes with Se in bovine liver.

: We measured the amount of Se in the tRNA fractions eluted from a BD-cellulose column. Se was found in the fraction eluted early from the column as to be 3 x 10(-4) mol/mol of tRNA. This low amount suggests that there is no tRNA species that contain 1 mol of Se per 1 mol of tRNA and only few specific tRNAs contain Se-nucleotides. Next, we searched the Se modification enzymes with this tRNA fraction and found the activity in cytosol. Now the digestions of the tRNA modified with 75Se was analyzed by two dimensional TLC. tRNA(Sec) of T7 transcript was not substrate for this enzyme.