2glk
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High-resolution study of D-Xylose isomerase, 0.94A resolution.
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
2GLK is a Single protein structure of sequence from Streptomyces rubiginosus with MN and GOL as ligands. 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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