Modulation of Enzyme Cascade Activity by Local Substrate Enrichment and Exclusion on DNA Nanostructures

Substrate confinement and channeling play a critical role in multienzyme pathways and are considered to impact the catalytic efficiency and specificity of biomimetic and artificial nanoreactors. Here we reported a modulation of a multienzyme system with the cascade activity impacted by the surface affinity binding to substrate molecules. A DNA origami modified with aptamers was used to bind and enrich ATP molecules in the local area of immobilized enzymes, thereby enhancing the activity of an enzyme cascade by more than 2-fold. Alternatively, DNA nanostructure modified with blocked aptamers does not bind with ATP, thereby reducing the activity of the enzyme cascade. The Michaelis-Menten kinetics showed decreased apparent K_M values (∼3-fold lower) for enzyme nanostructures modified with aptamers, suggesting the higher effective substrate concentration near enzymes due to the local enrichment of substrates. Conversely, increased apparent K_M values (∼2-fold higher) were observed for enzyme nanostructures modified with blocked aptamers, possibly due to the exclusion of substrates approaching the surface. The similar concept of this modified surface-substrate interaction should be applicable to other multienzyme systems immobilized on nanostructures, which could be useful in the development of biomimetic nanoreactors.