Experimental Determination of Zinc Isotope Fractionation in Complexes with the Phytosiderophore 2'-Deoxymugeneic Acid (DMA) and Its Structural Analogues, and Implications for Plant Uptake Mechanisms.
Experimental Determination of Zinc Isotope Fractionation in Complexes with the Phytosiderophore 2'-Deoxymugeneic Acid (DMA) and Its Structural Analogues, and Implications for Plant Uptake Mechanisms.
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DOI：
10.1021/acs.est.6b00566
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发表时间：
2017-01
影响因子：
11.4
通讯作者：
T. Marković;Saba Manzoor;E. Humphreys-Williams;G. Kirk;R. Vilar;D. Weiss
中科院分区：
文献类型：
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作者：
T. Marković;Saba Manzoor;E. Humphreys-Williams;G. Kirk;R. Vilar;D. Weiss
锌和其他金属的稳定同位素特征越来越多地被用于研究植物和土壤过程。与植物铁载体的络合反应是一个关键的反应，了解同位素分馏的控制是此类研究的核心。在这里，我们研究了锌离子与植物铁素载体2‘-脱氧互原酸(DMA)以及三种商业上可用的DMA结构类似物：EDTA、TmDTA和CyDTA络合过程中的同位素分馏。我们使用离子交换层析分离游离锌和络合锌，并确定了适合各个体系的阳离子交换树脂。它们是EDTA和CyDTA的Cherex-100，TmDTA的Amberlite CG50和DMA的Amberlite IR120。对于所有的配体，我们发现同位素重的锌以络合形式优先分配，并且分馏的程度与所用的锌与配体的比例无关，表明同位素平衡，分离结果不受分离过程中人工制品的显著影响。各组分(‰)分别为+0.33±0.07(1σ，n=3)、+0.45±0.02(1σ，n=2)、+0.62±0.05(1σ，n=3)和+0.30±0.07(1σ，n=4)。尽管锌配位的供体基团相似，但分馏因子明显不同，分馏程度似乎与络合稳定常数成正比。DMA的分级程度与田间试验中观察到的水稻对锌的吸收分级一致，支持DMA可能参与水稻对锌的吸收。
The stable isotope signatures of zinc and other metals are increasingly used to study plant and soil processes. Complexation with phytosiderophores is a key reaction and understanding the controls of isotope fractionation is central to such studies. Here, we investigated isotope fractionation during complexation of Zn2+ with the phytosiderophore 2'-deoxymugeneic acid (DMA), and with three commercially available structural analogues of DMA: EDTA, TmDTA, and CyDTA. We used ion exchange chromatography to separate free and complexed zinc, and identified appropriate cation exchange resins for the individual systems. These were Chelex-100 for EDTA and CyDTA, Amberlite CG50 for TmDTA and Amberlite IR120 for DMA. With all the ligands we found preferential partitioning of isotopically heavy zinc in the complexed form, and the extent of fractionation was independent of the Zn:ligand ratio used, indicating isotopic equilibrium and that the results were not significantly affected by artifacts during separation. The fractionations (in ‰) were +0.33 ± 0.07 (1σ, n = 3), + 0.45 ± 0.02 (1σ, n = 2), + 0.62 ± 0.05 (1σ, n = 3) and +0.30 ± 0.07 (1σ, n = 4) for EDTA, TmDTA, CyDTA, and DMA, respectively. Despite the similarity in Zn-coordinating donor groups, the fractionation factors are significantly different and extent of fractionation seems proportional to the complexation stability constant. The extent of fractionation with DMA agreed with observed fractionations in zinc uptake by paddy rice in field experiments, supporting the possible involvement of DMA in zinc uptake by rice.