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PDBsum entry 3ws5
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References listed in PDB file
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Key reference
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Title
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Structure of a highly acidic β-Lactamase from the moderate halophile chromohalobacter sp. 560 and the discovery of a cs(+)-Selective binding site.
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Authors
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S.Arai,
Y.Yonezawa,
N.Okazaki,
F.Matsumoto,
C.Shibazaki,
R.Shimizu,
M.Yamada,
M.Adachi,
T.Tamada,
M.Kawamoto,
H.Tokunaga,
M.Ishibashi,
M.Blaber,
M.Tokunaga,
R.Kuroki.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2015,
71,
541-554.
[DOI no: ]
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PubMed id
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Abstract
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Environmentally friendly absorbents are needed for Sr(2+) and Cs(+), as the
removal of the radioactive Sr(2+) and Cs(+) that has leaked from the Fukushima
Nuclear Power Plant is one of the most important problems in Japan. Halophilic
proteins are known to have many acidic residues on their surface that can
provide specific binding sites for metal ions such as Cs(+) or Sr(2+). The
crystal structure of a halophilic β-lactamase from Chromohalobacter sp. 560
(HaBLA) was determined to resolutions of between 1.8 and 2.9 Å in space group
P31 using X-ray crystallography. Moreover, the locations of bound Sr(2+) and
Cs(+) ions were identified by anomalous X-ray diffraction. The location of one
Cs(+)-specific binding site was identified in HaBLA even in the presence of a
ninefold molar excess of Na(+) (90 mM Na(+)/10 mM Cs(+)). From an activity
assay using isothermal titration calorimetry, the bound Sr(2+) and Cs(+) ions do
not significantly affect the enzymatic function of HaBLA. The observation of a
selective and high-affinity Cs(+)-binding site provides important information
that is useful for the design of artificial Cs(+)-binding sites that may be
useful in the bioremediation of radioactive isotopes.
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