2gub
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Crystal Structure of Metal Free D-Xylose Isomerase.
OverviewOverview
Time-of-flight neutron diffraction has been used to locate hydrogen atoms, that define the ionization states of amino acids in crystals of D-xylose, isomerase. This enzyme, from Streptomyces rubiginosus, is one of the, largest enzymes studied to date at high resolution (1.8 A) by this method., We have determined the position and orientation of a metal ion-bound water, molecule that is located in the active site of the enzyme; this water has, been thought to be involved in the isomerization step in which D-xylose is, converted to D-xylulose or D-glucose to D-fructose. It is shown to be, water (rather than a hydroxyl group) under the conditions of measurement, (pH 8.0). Our analyses also reveal that one lysine probably has an, -NH(2)-terminal group (rather than NH(3)(+)). The ionization state of each, histidine residue also was determined. High-resolution x-ray studies (at, 0.94 A) indicate disorder in some side chains when a truncated substrate, is bound and suggest how some side chains might move during catalysis., This combination of time-of-flight neutron diffraction and x-ray, diffraction can contribute greatly to the elucidation of enzyme, mechanisms.
About this StructureAbout this Structure
2GUB is a Single protein structure of sequence from Streptomyces rubiginosus. Active as Xylose isomerase, with EC number 5.3.1.5 Full crystallographic information is available from OCA.
ReferenceReference
Locating active-site hydrogen atoms in D-xylose isomerase: time-of-flight neutron diffraction., Katz AK, Li X, Carrell HL, Hanson BL, Langan P, Coates L, Schoenborn BP, Glusker JP, Bunick GJ, Proc Natl Acad Sci U S A. 2006 May 30;103(22):8342-7. Epub 2006 May 17. PMID:16707576
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