Selenite Reduction by the Thioredoxin System: Kinetics and Identification of Protein-Bound Selenide
Selenite Reduction by the Thioredoxin System: Kinetics and Identification of Protein-Bound Selenide
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DOI：
10.1271/bbb.100847
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
T. Tamura;Kumi Sato;Kentarou Komori;T. Imai;Mitsuhiko Kuwahara;Takahiro Okugochi;H. Mihara;N. Esaki;K. Inagaki
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文献类型：
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作者：
T. Tamura;Kumi Sato;Kentarou Komori;T. Imai;Mitsuhiko Kuwahara;Takahiro Okugochi;H. Mihara;N. Esaki;K. Inagaki
亚硒酸盐（SeO3 2−）同化为细菌硒蛋白依赖于大肠杆菌中的硫氧还蛋白（trx）还原酶，但其分子机制尚未阐明。矿物油覆盖法使得进行厌氧酶测定成为可能，该测定证明了初始滞后期，随后是时间依赖性的稳定 NADPH 消耗，并且对亚硒酸盐和 trx 具有正协同作用。使用 75Se 标记的亚硒酸盐作为底物的 SDS-PAGE/放射自显影显示反应混合物中形成了 trx 结合的硒。蛋白质结合的硒在稳定在二价状态方面具有代谢意义，并且它还通过大肠杆菌trx还原酶（TrxB）的催化产生硒过硫化物（-S-SeH）形式。
Selenite (SeO3 2−) assimilation into a bacterial selenoprotein depends on thioredoxin (trx) reductase in Esherichia coli, but the molecular mechanism has not been elucidated. The mineral-oil overlay method made it possible to carry out anaerobic enzyme assay, which demonstrated an initial lag-phase followed by time-dependent steady NADPH consumption with a positive cooperativity toward selenite and trx. SDS-PAGE/autoradiography using 75Se-labeled selenite as substrate revealed the formation of trx-bound selenium in the reaction mixture. The protein-bound selenium has metabolic significance in being stabilized in the divalent state, and it also produced the selenopersulfide (-S-SeH) form by the catalysis of E. coli trx reductase (TrxB).