A chemical approach to studies of the three-dimensional structure of tRNA - alkylation with a reagent covalently bound to a ‘peculiar site’

Abstract

Yeast valine tRNA₁ was chemically modified with chlorambucil N-hydroxysuccinimide ester. The reagent was attached covalently to the valine residue of valyl-tRNA₁^Val under the conditions which prevented tRNA from alkylation. Chlorambucilyl-valyl-tRITA₁^Val thus obtained was separated from excess reagent and incubated in an aqueous solution at neutral pH in the presence of Mg⁺⁺ ions. Highly efficient intramolecular Val self-alkylation of chlorambucilyl-valyl-tRNA₁^Val took place. The chlorambucil residue bound covalently to the amino group of the valine residue of tRNA₁^Valalkylates the 5′-terminal phosphate group of the molecule, and its 3′-terminal sequence -A-C-C-A.