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外源性重金属胁迫下香铃草子中巯基化合物中巯基的响应机制的研究
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摘要
植物对重金属的忍耐、吸附和超积累作用与植物细胞内的活性巯基化合物有关~([1])。因此,筛选富含巯基化合物的植物并探讨巯基对重金属胁迫的应答作用及相关化学机制具有实际意义~([2])。本文以Cu~(2+)、Hg~(2+)、Pb~(2+)、Cd~(2+)盐溶液浸泡胁迫(2h)富含巯基化合物的香铃草子的样品,分别用HPLC和ICP-MS测定了重金属胁迫前、后香铃草子细胞内还原型谷胱甘肽(GSH)和巯基蛋白(P-SH)中巯基含量变化及对应的胞内重金属吸附量的变化。结果发现:Hg~(2+)、Cu~(2+)的胁迫耗尽胞内GSH和P-SH的巯基且对应的胞内净吸附量分别为3185.667mg/g和1711.59mg/g。Pb~(2+)胁迫时胞内GSH巯基含量几近无变化,P-SH巯基含量略增、Cd~(2+)胁迫时GSH和P-SH巯基含量几近无变化,而对应的胞内净附量分别为1140.04mg/g和11.09mg/g,意味着Cu~(2+)和Hg~(2+)是与胞内巯基化合物的巯基直接作用吸附到细胞内,而Pb~(2+)和Cd~(2+)可能与非巯基的配位基团配位并吸附到细胞内。与胞内巯基直接作用的重金属具有较大的胞内吸附量,说明胞内巯基与外源性重金属的化学作用对重金属在胞内吸附中扮演最重要的角色。
Plant tolerance to heavy metals,adsorption,and accumulation are related to the active role of thiol compounds in plant cells.Thus,it is interesting to screen out plants rich in thiol compound and explore the response of thiol content on the exogenous heavy metal stress.The plant samples(Hibiscus trionum L.) were dipped by Cu~(2+),Hg~(2+),Pb~(2+),Cd~(2+) salt solution(2h) and were determined by HPLC and ICP-MS for reduced glutathione(GSH) and protein thiol content(P-SH) as well as adsorbed heavy metal amounts.It was found that the plant cell adsorbed heavy metals with the amounts of 3185.667mg/g for Hg~(2+),1711.59mg/g for Cu~(2+) accompanied by the depletion of GSH and P-SH thiols,and with the amounts of 1140.04 mg / g for Pb~(2+),11.09 mg / g for Cd~(2+) without significant changes of thiol content in the cell,indicating that the chemical interaction between thiol and exogenous heavy metals plays the most important role in intracellular adsorption.
引文
[1]S.K.Yadav.South African Journal of Botany,2010,76:167
    [2]原海燕,郭智,佟海英,黄苏珍.水土保持学报,2013,27(4):212

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