Selective substrate processing at single-atom resolution in a nanoscale tube
Researchers from the University of Oxford's Department of Chemistry have constructed a tubular protein nanoreactor that can selectively process polymers with atomic specificity.
Selective processing is achieved by nanoscale alignment of a substrate within a protein nanotube modified with a reactive group. The substrate is first pulled into the nanotube and extended by an applied electric field. Only substrates that are properly aligned, by design, with the reactive group on the nanotube are then processed. The system is versatile, allowing the reaction site to be altered by changing the design of the nanoreactor, the substrate, or both to obtain the desired alignment.
Using a collection of tubular nanoreactors, the authors processed various substrates containing a disulfide bond at a precise sulfur atom, demonstrating the ability to distinguish between two (or more) similar sites within a given functional group (regioselectivity) and within a given molecule (site-selectivity). Substrate processing was monitored at the single-molecule level, allowing the type of adduct formed to be identified based on the ionic conductance of the nanoreactor. Selective processing would not have been achievable in bulk solution, where differentiation of similar reactive sites is difficult if not impossible. Substrate turnover was also achieved by allowing a small molecule to diffuse into the nanotube to regenerate the reactive site after each cycle.
The full paper, Catalytic site-selective substrate processing within a tubular nanoreactor, can be read in the journal Nature Nanotechnology DOI: 10.1038/s41565-019-0579-7