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PDBsum entry 3kcl
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References listed in PDB file
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Key reference
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Title
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Metal ion roles and the movement of hydrogen during reaction catalyzed by d-Xylose isomerase: a joint X-Ray and neutron diffraction study.
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Authors
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A.Y.Kovalevsky,
L.Hanson,
S.Z.Fisher,
M.Mustyakimov,
S.A.Mason,
V.T.Forsyth,
M.P.Blakeley,
D.A.Keen,
T.Wagner,
H.L.Carrell,
A.K.Katz,
J.P.Glusker,
P.Langan.
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Ref.
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Structure, 2010,
18,
688-699.
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PubMed id
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Abstract
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Conversion of aldo to keto sugars by the metalloenzyme D-xylose isomerase (XI)
is a multistep reaction that involves hydrogen transfer. We have determined the
structure of this enzyme by neutron diffraction in order to locate H atoms (or
their isotope D). Two studies are presented, one of XI containing cadmium and
cyclic D-glucose (before sugar ring opening has occurred), and the other
containing nickel and linear D-glucose (after ring opening has occurred but
before isomerization). Previously we reported the neutron structures of
ligand-free enzyme and enzyme with bound product. The data show that His54 is
doubly protonated on the ring N in all four structures. Lys289 is neutral before
ring opening and gains a proton after this; the catalytic metal-bound water is
deprotonated to hydroxyl during isomerization and O5 is deprotonated. These
results lead to new suggestions as to how changes might take place over the
course of the reaction.
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