(650e) Intermediate Channeling Via Nanoscale Confinement

Multi-step, enzyme-catalyzed reaction cascades occur frequently in metabolic and catabolic pathways of living cells with high efficiency, selectivity, and yield. Understanding these metabolic pathways can lead to engineered synthetic pathways for the production energy and high-value molecules.

Transfer of intermediates between the active sites without diffusing into the bulk is known as â??substrate channeling.â? Confinement by molecular tunnels, electrically charged pathways, spatial organization of catalysts and covalent bonding of intermediates are examples of substrate channeling mechanisms. Under most relevant reaction conditions, the rate of diffusion is faster than the rate of reaction.^1 Hence, confining the active sites and intermediate by creating a physical tunnel between active sites enables controlled transport without bulk diffusion.

In the present study, computational modeling has been performed to study the effect of geometric, kinetic, and transport parameters on intermediate channeling via confinement, using a continuum model. Efficiency of transport is quantified by reactant yield and flux control coefficients (FCC).²Â Retention of intermediates within the tunnel, with minimal access to bulk solution, is shown to be the key to efficient channeling.

Acknowledgement

We gratefully acknowledge support from Army Research Office MURI (#W911NF1410263) via The University of Utah.

References

1. I. Wheeldon, S. D. Minteer, S. Banta, S. Calabrese Barton, P. Atanassov and M. Sigman, "Substrate channelling as an approach to cascade reactions", Nat. Chem., 8, 299â??309 (2016). doi:10.1038/nchem.2459.

2. D. A. Fell, "Metabolic control analysis: a survey of its theoretical and experimental development", Biochem. J., 330, 313â??330 (1992). doi:10.1042/bj2860313.