Figure 1.

(a) Structural organization of the HCV IRES (3). RNA sequences complementary to deoxy oligomers used for the site-specific modification of the HCV IRES are marked with hard lines. A sequence complementary to the helper oligomer used together with the alkylating derivative in hairpin IIIe is marked with dotted line. Arrows indicate 5′-termini of the oligomers derivatized with the alkylating groups. Nucleotides of the HCV IRES cross-linked to the oligonucleotide derivatives are shaded. (b) Scheme of site-specific introduction of a photoactivatable group into specific RNA sites based on the complementary-addressed alkylation of the RNA with [4-(N-2-chloroethyl-N-methylamino)benzyl]-phosphoramides of oligodeoxyribonucleotides.