(228m) Role of Dimension and Spatial Arrangement on the Activity of Coupled Biocatalytic Reactions on Scaffolds

Despite broad interest in engineering enzyme cascades on surfaces (i.e., for multi-step biocatalysis, enzyme-mediated electrocatalysis, biosensing, and synthetic biology), there is a fundamental gap in understanding about how the local density and spatial arrangement of enzymes impacts overall activity. In this work, the dependence of the overall activity of a cascade reaction on geometric arrangement and density of enzymes immobilized on a two-dimensional scaffold was elucidated using de novo kinetic Monte Carlo simulations. Simulations were specifically used to track the molecular trajectories of the reaction species and to investigate the turnover frequency of individual enzymes on the surface under diffusion-limited and reaction-limited conditions for random, linear striped, and hexagonal arrangements of the enzymes. Interestingly, the simulation results showed that, under diffusion-limited conditions, arrangements with the shortest distance between sequential enzymes were favored at high enzyme surface densities. Conversely, under reaction-limited conditions, the spatial arrangement of enzymes did not impact the overall rate. These results, which have widespread practical implications, suggest that random immobilization of the enzymes yields similar rates to enzyme arrangements that may be achieved using sophisticated approaches to patterning, thereby simplifying the engineering of artificial biocatalytic cascades.