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Arai, Shigeki; Yonezawa, Yasushi*; Okazaki, Nobuo*; Matsumoto, Fumiko*; Shibazaki, Chie; Shimizu, Rumi; Yamada, Mitsugu*; Adachi, Motoyasu; Tamada, Taro; Kawamoto, Masahide*; et al.
Acta Crystallographica Section D, 71(3), p.541 - 554, 2015/03
Times Cited Count:7 Percentile:50.54(Biochemical Research Methods)The crystal structure of halophilic -lactamase from sp.560 (HaBLA) was determined using X-ray crystallography. Moreover, the locations of bound Sr and Cs ions were identified by anomalous X-ray diffraction. The location of one Cs specific binding site was identified on HaBLA even in the presence of 9-fold molar excess of Na (90 mM Na /10 mM Cs). This Cs binding site is formed by two main-chain O atoms and an aromatic ring of a side chain of Trp. An aromatic ring of Trp interacts with Cs by the cation- interaction. The observation of a selective and high-affinity Cs binding site provides important information that is useful for designing artificial Cs binding sites useful in bioremediation of radioactive isotopes.
Arai, Shigeki; Adachi, Motoyasu; Tamada, Taro; Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota
no journal, ,
Because various metal ion binding sites exist on halophilic proteins, we proposed that the metal ion binding sites with an affinity to harmful metals and rare metals could be identified using X-ray crystallographic analysis in the presence of those metal ions. In this study, we attempted to identify metal ion binding sites for Sr and Cs on a halophilic protein HaBLA derived from sp.560 (HaBLA) by X-ray crystallographic analysis and anomalous X-ray diffraction analysis. By these analyses, we succeeded in discovering one Cs binding site and three Sr binding site for one molecule of HaBLA. Moreover, discovered Cs binding site showed high Cs selectivity, which binds Cs even in the presence of 9-fold molar excess of Na (90 mM Na / 10 mM Cs).