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Hydrogen Location in Stages of an Enzyme-Catalyzed Reaction: Time-of-Flight Neutron Structure of D-Xylose Isomerase with Bound D-Xylulose

Journal Article · · Biochemistry (American Chemical Society)
OSTI ID:1033969
The time-of-flight neutron Laue technique has been used to determine the location of hydrogen atoms in the enzyme D-xylose isomerase (XI). The neutron structure of crystalline XI with bound product, D-xylulose, shows, unexpectedly, that O5 of D-xylulose is not protonated but is hydrogen-bonded to doubly protonated His54. Also, Lys289, which is neutral in native XI, is protonated (positively charged), while the catalytic water in native XI has become activated to a hydroxyl anion which is in the proximity of C1 and C2, the molecular site of isomerization of xylose. These findings impact our understanding of the reaction mechanism.
Research Organization:
Oak Ridge National Laboratory (ORNL)
Sponsoring Organization:
ORNL LDRD Director's R&D; SC USDOE - Office of Science (SC)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1033969
Journal Information:
Biochemistry (American Chemical Society), Journal Name: Biochemistry (American Chemical Society) Journal Issue: 10 Vol. 1; ISSN 0006-2960; ISSN BICHAW
Country of Publication:
United States
Language:
English

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