A conceptually simple method for the covalent attachment of an RNA to an NHS-modified support. (A) An RNA bearing an alkylamine tether, whether located at the 5′ end of the RNA or elsewhere, ought to react through a direct nucleophilic attack at the N-hydroxysuccinimidyl-ester activated carbonyl. This direct coupling proved too inefficient for the preparation of a large-capacity column. (B) Two sequences were used for the synthesis of RNA columns. The RNA 5′-NH2-C-IRE corresponds to a consensus iron-responsive element sequence, and has a 5-atom alkyl-ether amine tether appended to the 5′ terminal phosphate. The negative control, 5′-NH2-N-IRE is similarly modified with a 5′-alkylamine tether, but has a sequence that is the exact complement of the consensus IRE.
