La(Ⅲ)、Eu(Ⅲ)与HBED配合的紫外差光谱研究  

UV Difference Spectra Studies on the Binding of La（Ⅲ） and Eu（Ⅲ） to HBED

作　　者：白海静[1] 刘文[1] 杨斌盛[1] 

机构地区：[1]山西大学分子科学研究所,太原030006

出　　处：《无机化学学报》2001年第3期389-394,共6页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金资助项目(No.20071022);山西省自然科学基金资助课题(No.991013)。

摘　　要：在０．０１ｍｏｌ·　Ｌ－１Ｎ－２－羟乙基哌嗪－Ｎ’－２－乙磺酸（Ｈｅｐｅｓ），　ｐＨ　７．４，室温条件下，用紫外差光谱滴定观察了Ｌａ（Ⅲ），Ｅｕ（Ⅲ）与Ｎ，Ｎ’－二（２－羟苄基）乙二胺－Ｎ，Ｎ’－二乙酸（ＨＢＥＤ）的结合。Ｌａ（Ⅲ），Ｅｕ（Ⅲ）与ＨＢＥＤ的结合均形成　１：　ｌ的配合物，其紫外差光谱均于２３８和２９２ｎｍ处出现吸收峰，在２３８ｎｍ处配合物Ｌａ－ＨＢＥＤ与Ｅｕ－ＨＢＥＤ的摩尔吸光系数分别为：εＬａ＝（９．８２±０．２４）×　１０３ｃｍ－１·ｍｏｌ－１，Ｌ，εＥｕ＝（ｌ６．２１　±０．１２）×　１０３ｃｍ－１·ｍｏｌ－１·Ｌ；配合物Ｌａ－ＨＢＥＤ与Ｅｕ－ＨＢＥＤ的条件稳定常数分别为：ｌｇＫＬａ－ＨＢＥＤ＝１１．５２±０．２２，ｌｇＫＥｕ－ＨＢＥＤ＝１４．１６±０．３８，符合线性自由能关系。人血清脱铁转铁蛋白和Ｅｕ　（Ⅲ）结合的紫外差光谱与ＨＢＥＤ和ＥＵ　（Ⅲ）结合的紫外差光谱相似，只是最大吸收峰红移至　３４５和　２９６ｎｍ，脱铁转铁蛋白不能与　Ｌａ（Ⅲ）结合。In 0. 01mol· L-l N-(2-hydroxyethyl) -piperazine-N'-2-ethanesulfonic acid (Hepes), at room temperature and pH 7. 4, the reaction N, N'-Bis(2-hydroxybenzyl) ethylenedinitrilo-N, N'-diacetic acid(HBED) with La (Ⅲ) or Eu （Ⅲ） was monitored by UV difference spectrophotometry. The molar absorptivities for La-HBED and Eu-HBED complexes are εLa = (9. 82 ± 0. 24) × 103cm-l· mol- I· L, △εEu = (16. 21± 0. 12) × 103cm- l· mol- 1· L, respectively. When EDTA was added, the UV difference peak at 238urn of La-HBED or Eu-HBED decreased. Using EDTA as competing agent conditional equilibrium constants for the complexes were measured. They are lgKLa-HSED = 11. 52 ± 0. 22 and lgKEu-HBED = 14. 16 ±0. 38. A linear free energy relationship for the complexes of Lanthanum and Europium has been established by using equilibrium data on 19 complexes produced by these metal ions with low molecular weight ligands. The HBED binding constants for La (Ⅲ) and Eu (Ⅲ) are in agreement with the linear free energy relationship. Under the same conditions the human serum apotransferrin(apoTf) has been titrated with La (Ⅲ）, Eu（Ⅲ）. The UV difference spectrophotometry for the binding ｏf Eu (Ⅲ) with apoTf is similar to that of Eu （Ⅲ） with HBED, except a little red shift of the maximum absorptivity peaks. The binding Of La (Ⅲ) with apoTf, however, hardly happens.

关 键 词：转铁蛋白 HBED 紫外差光谱 镧(Ⅲ) 铕(Ⅲ) 配合物 N N′-二(乙-羟苄基)乙二胺-N N′-二乙酸) 

分 类 号：Q51[生物学—生物化学] O614.33[理学—无机化学]