Modular Catalysis: Aptamer Enhancement of Enzyme Kinetics in a Nanoparticle Reactor

Enzyme activity requires sequential binding and chemical transformation of substrates. While directed evolution and random mutagenesis are common methods for improving catalytic activity, these methods do not allow for independent control of K_M and k_cat. To achieve such control, we envisioned that the colocalization of aptamers and enzymes that act on the same molecule could increase catalytic efficiency through preconcentration of substrate. We explored this concept with cocaine esterase and anticocaine aptamers having varying K_D values, both encapsulated in MS2 virus-like particles. Rate enhancements were observed with magnitudes dependent on both aptamer:enzyme stoichiometry and aptamer K_D, peaking when aptamer K_D and enzyme K_M were roughly equivalent. This beneficial effect was lost when either aptamer binding was too tight or the aptamers were not constrained to be close to the catalyst. This work demonstrates a modular way to enhance catalysis by independently controlling substrate capture and release to the processing enzyme.