Studies on transfer ribonucleic acids and related compounds. XL.1 Synthesis of an eicosaribonucleotide corresponding to residues 35–54 of tRNAfMet from E. coli

摘要

An E.coli tRNA_fMet fragment [C-A-U-A-A-C-C-C-G-A-A-G-G-U-CG-U-C-G-G (bases 35–54)] containing the anticodon triplet has been synthesized by the phosphotriester method involving protected oligonucleotide blocks. Di- or tri-nucleotide blocks were prepared by condensation of 2′-O-(o-nitrobenzyl)nucleotide derivatives and used for the synthesis of pentanucleotide blocks. The 5′-hydroxy, heterocyclic amino and internucleotide linkage were protected with monomethoxytrityl, acyl and p-chlorophenyl groups, respectively. The 3′-phosphates of the pentanucleotides, except for the GUCGG block where 2′-0-benzoyl 3′-O-(o-nitrobenzyl) N-isobutyrylguanosine was used, were protected with pchlorophenyl and anilido groups. The anilido groups were removed by treatment with isoamyl nitrite and the 3′-phosphodiesters of resulting pentamers were activated with mesitylenesulfonyl nitrotriazolide to give protected decanucleotides in yields of 61–89%. The two decanucleotides were condensed similarly to yield the protected eicosanucleotide in a yield of 59%. The product was deblocked and purified by ion-exchange chromatography on DEAE-Sephadex A-25 and characterized by enzymatic hydrolysis after labelling the 5′-end by phosphorylation using polynucleotide kinase and [γ-32p]ATP.