A Rhodococcus erythropolis bacterium that tolerates normally lethal concentrations of Fe(II), Cu(II), AsO₃²⁻, SeO₃²⁻, TeO₃²⁻, Cd(II) and Zn(II) was identified from an environmental isolate. In characterizing the molecular basis for metal tolerance, a mycothione reductase (Mtr) with remarkable selectivity for TeO₃²⁻ reduction over SeO₃²⁻ was identified. In equimolar concentrations of TeO₃²⁻ and SeO₃²⁻, the enzymatic product contains a 7-fold excess of Te. This selectivity is remarkable because the standard reduction potential of SeO₃²⁻ is 0.20 V more favorable for reduction than TeO₃². Selectivity of the enzyme for TeO₃²⁻ decreases with increasing assay pH. Homology modeling of the enzyme identifies four aromatic residues near the active site, including two histidine residues, that are not present in a related SeO₃²⁻ preferring reductase. On the basis of more favorable π-interactions for Te than for Se and the pH dependence of the selectivity, the Te-selectivity is attributed in part to these aromatic residues. The resulting Te⁰ enzymatic product resembles Te nanowires.

中文翻译：

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从红球菌 PR4 中鉴定 TeO32−还原酶/霉菌硫酮还原酶

从环境分离株中鉴定出一种能够耐受正常致死浓度 Fe(II)、Cu(II)、AsO ₃ ²⁻、SeO ₃ ²⁻、TeO ₃ ²⁻、Cd(II) 和 Zn(II)的红球菌红球菌. 在表征金属耐受性的分子基础时，鉴定了一种霉菌硫酮还原酶 (Mtr)，其对 TeO ₃ ^2-还原比 SeO ₃ ^2-具有显着的选择性。在等摩尔浓度的 TeO ₃ ^2-和 SeO ₃ ^{2- 中}，酶产物含有 7 倍过量的 Te。这种选择性非常显着，因为 SeO 的标准还原电位₃ ^2-比TeO ₃ ²有利于还原的0.20V 。酶对 TeO ₃ ^{2- 的}选择性随着测定 pH 值的增加而降低。该酶的同源性建模确定了活性位点附近的四个芳族残基，包括两个组氨酸残基，它们不存在于相关的 SeO ₃ ^2-偏好还原酶中。基于Te 比 Se更有利的π相互作用以及选择性的 pH 依赖性，Te 选择性部分归因于这些芳香族残基。所得的 Te ⁰酶产物类似于 Te 纳米线。