Laccase-catalyzed oxidation of iodide and formation of organically bound iodine in soils
Laccase-catalyzed oxidation of iodide and formation of organically bound iodine in soils
复制标题
漆酶催化的碘化物氧化和土壤中有机结合碘的形成
DOI：
10.1021/es303228n
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发表时间：
2013
影响因子：
11.4
通讯作者：
S.
中科院分区：
文献类型：
--
作者：
Seki;M.;Oikawa;J.;Taguchi;T.;Ohnuki;T.;Muramatsu;Y.;Sakamoto;K.;and Amachi;S.
漆酶将碘化物氧化成分子碘或次碘酸，这两者都很容易融入天然土壤有机质中。在这项研究中，在不同的实验条件下测定了两种日本土壤中的碘化物吸附和漆酶活性，以评估该酶可能参与碘化物的吸附。使用放射性碘示踪剂（125I–）进行的批量吸附实验表明，高压灭菌（121℃，40分钟）、热处理（80和100℃，10分钟）、γ射线照射（30kGy）、氮气冲洗以及添加还原剂和一般漆酶抑制剂（KCN和NaN3）均显着抑制吸附。有趣的是，在土壤漆酶活性中观察到非常相似的抑制趋势，这是使用 2,2'-azino-bis(3-乙基苯并噻唑啉-6-磺酸盐) (ABTS) 作为底物测定的。两个土壤样品中碘化物的分配系数（Kd：mL g-1）和土壤中漆酶的比活性（单位g-1）均显示出显着的正相关。向土壤中添加具有碘化物氧化活性的细菌漆酶可强烈增强碘化物的吸附。此外，酶的添加部分恢复了高压灭菌土壤样品的碘化物吸附能力。这些结果表明微生物漆酶通过碘化物的氧化参与土壤上碘化物的吸附。
Laccase oxidizes iodide to molecular iodine or hypoiodous acid, both of which are easily incorporated into natural soil organic matter. In this study, iodide sorption and laccase activity in 2 types of Japanese soil were determined under various experimental conditions to evaluate possible involvement of this enzyme in the sorption of iodide. Batch sorption experiment using radioactive iodide tracer (125I–) revealed that the sorption was significantly inhibited by autoclaving (121 °C, 40 min), heat treatment (80 and 100 °C, 10 min), γ-irradiation (30 kGy), N2gas flushing, and addition of reducing agents and general laccase inhibitors (KCN and NaN3). Interestingly, very similar tendency of inhibition was observed in soil laccase activity, which was determined using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as a substrate. The partition coefficient (Kd: mL g–1) for iodide and specific activity of laccase in soils (Unit g–1) showed significant positive correlation in both soil samples. Addition of a bacterial laccase with an iodide-oxidizing activity to the soils strongly enhanced the sorption of iodide. Furthermore, the enzyme addition partially restored iodide sorption capacity of the autoclaved soil samples. These results suggest that microbial laccase is involved in iodide sorption on soils through the oxidation of iodide.