镧、铈和铽作用于细胞的靶点差异  

Different targets of lanthanum(Ⅲ),cerium(Ⅲ) and terbium(Ⅲ) action on cells

作　　者：杨清[1,2] 王丽红[1,2] 何婧芳 周青[1] 黄晓华[2] 

机构地区：[1]江南大学食品科学与技术国家重点实验室,无锡214122 [2]江苏省生物医药功能材料协同创新中心,南京师范大学化学与材料科学学院,南京210023

出　　处：《中国科学：化学》2016年第9期859-866,共8页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:21371100,31170477,21501068);高等学校博士学科点专项基金新教师类(编号:20130093120006);江苏省优势学科资助项目

摘　　要：稀土可通过食物链进入生命体并累积已成为不争的事实,但稀土离子的植物细胞化学行为尚不清楚.本文通过^(140)La(Ⅲ)、^(141)Ce(Ⅲ)、^(160)Tb(Ⅲ)在植物体内放射自显影技术和量子化学计算等研究发现,化学性质相似的稀土离子La(Ⅲ)、Ce(Ⅲ)、Tb(Ⅲ)在细胞质膜和质膜外作用靶点显著不同,即Ce(Ⅲ)主要与质膜物质发生键合,La(Ⅲ)还能与细胞质膜外的细胞外物质和胞外基质分子键合,Tb(Ⅲ)更可与细胞壁物质键合;La(Ⅲ)和Tb(Ⅲ)与胞吞作用进入细胞的物质发生键合而进入细胞,Ce(Ⅲ)尚未观察到此现象;La(Ⅲ)和Tb(Ⅲ)与细胞质膜和质膜外物质通过配位共价键及分子间氢键形成稳定的路易斯酸碱配合物,Ce(Ⅲ)则可能仅靠库仑力与细胞质膜物质发生作用.由此导致La(Ⅲ)、Ce(Ⅲ)、Tb(Ⅲ)3种离子对细胞的作用靶点具有明显选择性,其中Ce(Ⅲ)的选择性>La(Ⅲ)>Tb(Ⅲ).可见,3种稀土离子不同数量f电子的成键活性所致细胞质膜及膜外靶分子键长、键角等参数差异,将导致下游信号转导及细胞化学行为迥异,终致其毒理不同.本文结果可为科学探究稀土累积对生物危害的细胞学机理提供新的思考与借鉴,也为稀土食品安全及人类健康预防提供重要指导.It is indisputable that rare earth elements（REEs） can accumulate in organisms through food chain.However,the cytochemical behaviours of REEs are still unknown.Here,by using electron microscopic autoradiography of ^140La（Ⅲ）,^141Ce（Ⅲ） and ^160Tb（Ⅲ） in plants and quantum chemical calculation etc.,it was discovered that these REEs,which have similar chemical properties,interacted with different targets in/out of plasma membrane.Ce（Ⅲ） mainly bound to substances in plasma membrane,La（Ⅲ） also bound to the substances of cellular matrix and cell coat,and Tb（Ⅲ） could even bind to substances in cell wall.La（Ⅲ） and Tb（Ⅲ） could enter cells by binding to these substances entered cells through endocytosis,however,Ce（Ⅲ） was not observed to have this behaviour.La（Ⅲ） and Tb（Ⅲ） could form stable Lewis acid-base complexes with substances in/out of plasma membrane by forming coordination bonds and hydrogen bonds,while Ce（Ⅲ） could bind to substances in plasma membrane only through electrostatic force.Therefore,these REEs obviously presented different selectivity in binding targets,which is the selectivity of Ce（Ⅲ）〉La（Ⅲ）〉Tb（Ⅲ）.Thus,the different binding activities of these three REEs,which originate from the different number of f electrons,would result in different parameters（such as bond length,angle,etc.） of the targets in/out of plasma membrane,and then this would make different downstream signal transduction and cytochemical behaviors,which would finally show different toxic effects.The results could provide some new thinking and references for scientifically assessing the damage effect of the accumulation of REEs on living orgnaisms and the environmental risk of REEs,and also provide the important guides for food safety and human health.

关 键 词：稀土 镧 铈 铽 细胞化学行为 

分 类 号：Q942[生物学—植物学] O641.4[理学—物理化学]