Metalloenzyme-like catalyzed isomerizations of sugars by Lewis acid zeolites

[EN] Isomerization of sugars is used in a variety of industrially relevant processes and in glycolysis. Here, we show that hydrophobic zeolite beta with framework tin or titanium Lewis acid centers isomerizes sugars, e.g., glucose, via reaction pathways that are analogous to those of metalloenzymes. Specifically, experimental and theoretical investigations reveal that glucose partitions into the zeolite in the pyranose form, ring opens to the acyclic form in the presence of the Lewis acid center, isomerizes into the acyclic form of fructose, and finally ring closes to yield the furanose product. The zeolite catalysts provide processing advantages over metalloenzymes such as an ability to work at higher temperatures and in acidic conditions that allow for the isomerization reaction to be coupled with other important conversions.The work at Caltech and the University of Delaware was financially supported as part of the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-SC0001004. M.M acknowledges the Fundacion Ramon Areces Postdoctoral Research Fellowship Program and the "Subprograma Ramon y Cajal" for Contract RYC-2011-08972 for financial support. R.B.D. acknowledges the Obra Social "la Caixa" for a graduate fellowship. A.P. acknowledges the Caltech Summer Undergraduate Research Fellowship program(SURF) for financial support. The computational studies for this work were supported by the U.S. Department of Energy under Contract DE-AC0206CH11357 and this material is based upon work supported as part of the Institute for Atom-efficient Chemical Transformations (IACT), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences. We gratefully acknowledge grants of computer time from the ANL Laboratory Computing Resource Center (LCRC), and the ANL Center for Nanoscale Materials. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Sciences of the U.S. Department of Energy under Contract DE-AC02-05CH11231.Bermejo-Deval, R.; Assary, RSA.; Nikolla, E.; Moliner Marin, M.; Roman, Y.; Hwang, S.; Palsdottir, AP.... (2012). Metalloenzyme-like catalyzed isomerizations of sugars by Lewis acid zeolites. Proceedings of the National Academy of Sciences. 109(25):9727-9732. https://doi.org/10.1073/pnas.1206708109972797321092