How Sugars Pucker Up: An Electronic Structure Perspective

Heather Mayes, Northwestern University

Left to their own devices, the six-membered rings of sugars found in cellulose, hemicellulose, and chitin adopt a preferred stable, low-energy conformation. To cleave polysaccharides into monomeric sugars, glycosidase enzymes distort rings into puckered conformations along a catalytic itinerary specific to the enzyme's family. It has been postulated that enzymes distort the rings in order to accumulate positive charge on the pyranose ring. Using high-level ab initio calculations, we are able to map the electronic structure of the different puckered conformations to test this hypothesis and determine whether the different catalytic pathways for different sugars each make use of the conformations with the most oxocarbenium ion character. These insights will be significant for effective design of both enzymes and enzyme inhibitors, which have wide-ranging applications ranging from designing enzymatic inhibitors for biomedical sciences, to cellulose conversion for biofuel production, to understanding carbon and nitrogen turnover in the biosphere.

Abstract Author(s): Heather B. Mayes, Northwestern University, and Gregg T. Beckham, NREL