title: The lighter side of a sweet reaction.
abstract: The unique advantage of neutrons as biological probes is the ability to visualize hydrogen atoms in macromolecules. In this issue, Kovalevsky et al. (2010) solved an ensemble of xylose isomerase structures by neutron crystallography, and the determination of hydrogen atom rearrangements during the catalytic cycle provides insight into the enzyme's mechanism.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors.forename: Brad C
authors.initials: BC
authors.lastname: Bennett
authors.forename: Mark
authors.initials: M
authors.lastname: Yeager