In vitro selection of DNA aptamers that bind l-tyrosinamide Original Research Article

We have applied SELEX (Systematic Evolution of Ligands by EXponential enrichment), a combinatorial method that employs biopolymers for drug discovery, to identify single stranded DNA sequences able to bind l-Tyrosinamide, a simple mimic of Tyrosine, an amino acid essential to the catalytic activity of several enzymes of pharmaceutical interest. After 15 SELEX cycles using l-Tyrosinamide immobilized on an affinity chromatography column, the percentage of aptamers specifically eluted from the affinity column with free l-Tyrosinamide was 55% of the total. Aptamers were subcloned and sequenced, allowing the identification of a highly conserved consensus sequence, and showed a Kd value for l-Tyrosinamide of 45 μM. The identified aptamer sequence will constitute the basis for further in vitro evolution protocols and structure-based drug design.