The reaction of adenine and cytosine residues in tRNA with chloroacetaldehyde

The reaction of Lupinus luteus tRNAPhe with 1 M chloroacetaldehyde in the pH range of 4 - 6 at 25 degrees C was studied. It was found that earlier difficulties lowering the utility of the reagent for structural studies of nucleic acids were caused by the formation of the stable reaction intermediates. In order to eliminate these difficulties the simple procedure of so-called maturation of the chloroacetaldehyde-modifies tRNA is proposed. It consists in further incubation of the short-term modified tRNA in water at 50 degrees C in the absence of the reagent. During the maturation step the stable intermediates are quantitatively converted into final ethenoderivatives. New HPLC conditions on Aminex A-6 were worked out which enable rapid separation of both ethenoadenosine and ethenocytidine from natural tRNA nucleosides.