High Efficiency Acetylcholinesterase Immobilization on DNA Aptamer Modified Surfaces

We report here the in vitro selection of DNA aptamers for electric eel acetylcholinesterase (AChE). One selected aptamer sequence (R15/19) has a high affinity towards the enzyme (K-d = 157 +/- 42 pM). Characterization of the aptamer showed its binding is not affected by low ionic strength (similar to 20 mM), however significant reduction in affinity occurred at high ionic strength (similar to 1.2 M). In addition, this aptamer does not inhibit the catalytic activity of AChE that we exploit through immobilization of the DNA on a streptavidin-coated surface. Subsequent immobilization of AChE by the aptamer results in a 4-fold higher catalytic activity when compared to adsorption directly on to plastic.