[Complementarily addressed alkylation of yeast tRNA 1 Val with chloroethylmethylaminobenzylidene d(pC-G)-A. Proof of the modification of the third nucleotide located at the 5'-terminus of the complete binding site of the reagent].

Yeast tRNAlVal alkylation with 2',3'-0-[4-(N-2-chloroethyl-N-methylaminobenzylidene]dpCdpGrpA proceeds within complementary complexes that are formed due to attachment of the reagent to three sequences of tRNAlVal. The acetal bond of the initial product of alkylation has been hydrolyzed to yield beta-[N=methyl-N-(4-formylphenyl) amino]ethyl-tRNAlVal (R-tRNA) that contains from 1 to 3 residues of the specifically modified nucleosides: alkyl adenosine (R-A), R-I and probably R-psi. Individual alkylated oligonucleotides were isolated from R-tRNAlVal pyrimidyl-RNAse digest. The alkylated oligonucleotides correspond to 93% of all modified products. The major component is beta-[N-methyl-N(4-formylphenyl)aminoA1ethyl-A53-G-Tp. This indicates that the reagent is attached to complementary psi-C-G-sequence in the T-loop of tRNAlVal and that alkylation of the third nucleotide counting from the 5'-terminus of the sequence which binds the reagent completely takes place within the complementary complexes. This site of the tRNAlVal is modified quantitatively at 20 degrees and 19-fold excess of the reagent. The alkylation of two other sites of tRNA reaches 50% under these conditions.