稀土离子与伴清蛋白结合的紫外差光谱研究

在ｐＨ７．４ ,２５ ℃的条件下, 使用紫外吸收差光谱进行了Ｅｕ３＋ ,Ｔｂ３＋ ,Ｌｕ３＋ 对脱铁伴清蛋白的滴定。结果表明, 稀土离子与脱铁伴清蛋白结合后其差光谱均在２４４ 和２９４ ｎｍ 处给出吸收峰, 在２４４ ｎｍ 处, 稀土离子脱铁伴清蛋白络合物的摩尔吸光系数相近, 约为（２．１ ±０．１） ×１０４ ｃｍ －１·ｍｏｌ－ １·Ｌ;稀土离子可占据脱铁伴清蛋白的两个金属离子结合部位, 但优先占据脱铁伴清蛋白的Ｎ端结合部位。Ｃ端结合部位与稀土离子的结合量受ＣＯ２ －３ 浓度及离子半径的影响, 离子半径越大、ＣＯ２－３ 浓度越高,稀土离子在该部位的结合量越少。     

镧在Wistar大鼠肝脏中的物种分布

采用ICP MS、凝胶过滤层析及超滤技术 ,通过动物实验研究了长时间、低剂量镧作用后 ,镧在Wistar大鼠肝脏中的代谢累积及其物种分布。结果表明 ,随着给药剂量的增加及作用时间的增长 ,镧在肝脏中的累积量有规律地增大 ;停止给药一段时间后 ,积累在肝脏中的镧有不同程度的代谢 ,其代谢速度很慢 ;累积在肝脏中的镧主要分布于分子量大于 6 0 0 0 0的水溶性蛋白中 ;经SephacrylS 2 0 0层析分离得到的六个蛋白洗脱峰中均含有稀土 ,在第一个洗脱峰中含量最大 ,约占肝脏含镧大分子蛋白 (分子量大于 6 0 0 0 0 )总量的 88%     

二巯基丁二酸对~(210)铅组织分布和蛋白结合影响(摘要)

研究了二巯基丁二酸对铅的解毒作用。方法：小鼠iv210铅370kBq后，ig或ip二巯基丁二酸，剂量为1．0g·kg－1，用整体放射自显影术定位显示；大鼠210铅中毒后，用凝胶色谱法分离血清、肝、肾和尿，测定210铅与蛋白结合。结果：定位分布显示，对照小鼠肾脏210铅含量最高，肝、脾、肺、心、骨含量其次，脑内含量最低。给药后，大部分组织210铅含量明显减少。整体自显影片微光密度测定与相同部位组织用液门测定结果基本一致，大鼠血清和肝脏分离得到3个不同相对分子质量210铅蛋白复合物，肾脏仅有大分子210铅蛋白复合物，尿中主要为低相对分子质量非蛋白复合物。给药动物血清、肝脏和肾脏蛋白复合物与对照相似，但放射性含量低于对照，而尿中复合物210铅明显高于对照。结论：二巯基丁二酸对铅的解毒，减少了铅在体内各脏器中的沉积，以及与蛋白结合，促进其随尿液排出。     

金属硫蛋白溶液聚合状态的研究

通过动态光散射实验首次证明了兔肝金属硫蛋白亚型 和 在不同的缓冲体系中不仅仅是以二聚体的形式 ,而且是以多种聚合形式存在[1] .深入考察金属硫蛋白在溶液中的聚合形式对于研究金属硫蛋白的结构和功能都具有非常重要的意义 .我们通过计算机模拟 [1] 比较系统地研究了各种因素对金属硫蛋白聚合的影响 .结果表明 ,在溶液聚合的分子识别过程中可由多种因素共同调控金属硫蛋白 ,这些因素主要包括静电相互作用、疏水性相互作用和溶液中阴阳离子等 .通过这些因素的综合分析 ,首次对兔肝金属硫蛋白在溶液中多种聚合形式的形成机制及相应的分子…     

La3+诱导钙调蛋白与鼠脑组织钙调蛋白亲合蛋白的结合

应用固定化钙调蛋白(CaM)亲合色谱法、变性丙烯酰胺电泳(SDS-PAGE)和基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)等方法研究了La3+诱导CaM在大鼠脑匀浆液中的钙调蛋白亲合蛋白(CaMBP)谱以及CaM-CaMBP在模拟细胞环境下结合作用的La3+浓度依赖关系, 并与Ca2+的作用进行了比较. 实验结果表明, (1) La3+参与的CaMBP物种与Ca2+的基本相同. 鉴定了其中含量高且稳定出现的5种CaMBP分别是参与糖酵解反应的6-磷酸果糖激酶和3-磷酸甘油醛脱氢酶、细胞骨架类的微管蛋白和肌动蛋白以及应激反应相关的71000热休克同源蛋白, 表明稀土离子可能参与多种细胞过程; (2) La3+诱导CaM与5种CaMBP结合的浓度依赖曲线因CaMBP物种的不同而存在差别. 热休克同源蛋白、肌动蛋白或微管蛋白对La3+相对敏感, La3+在金属-CaM-CaMBP三元体系中与CaM的结合常数K与Ca2+的相近或稍高; 而6-磷酸果糖激酶和3-磷酸甘油醛脱氢酶体系对La3+的敏感性明显低于Ca2+. 其原因可能在于模拟细胞环境的复杂性以及CaM-CaMBP蛋白质相互作用对金属离子与CaM配位结合的调节.     

稀土离子诱导钙调蛋白构象变化后的单克隆抗体制备

采用单克隆抗体技术研究了三价稀土离子与钙调蛋白作用后对其与靶分子识别能力的影响。牛脑钙调蛋白经2.4-二硝基氟苯修饰后再结合三价的铕离子,然后免疫Balb/c小鼠,经过3次免疫后在小鼠血清中检测到相应的抗体,抗体效价为1:12000;用杂交瘤细胞技术制备出一株抗钙调蛋白的单克隆抗体细胞株2C3;酶联免疫吸附法(ELISA)测定结果证实钙调蛋白结合稀土离子前后对该抗体的识别能力存在显着差异,表明该抗体可以用于进一步研究金属离子对钙调蛋白构象变化及其对靶分子识别的影响。     

孕鼠胎盘膜对混合稀土常乐的屏障作用

为评估混合稀土常乐对人体胚胎的潜在危害, 在光镜和电镜下观察了混合稀土常乐染毒后的胎盘组织, 以了解其在胎盘组织中的存在形式和分布情况, 同时应用电感耦合等离子体质谱法(ICP-MS)检测染毒后的孕鼠血清、胚胎组织提取液和羊水中的稀土含量以确定其能否通过胎盘屏障. 染毒于雌鼠妊娠第六天开始, 每天分别以0.3, 2, 5和20 mg·kg-1混合稀土常乐灌胃, 直至妊娠第十八天. 结果显示: 光镜下, 染毒组胎盘绒毛中毛细血管周围合体细胞滋养层胞质内积聚有许多圆形黑色细小颗粒, 颗粒的多少与染毒剂量呈正相关; 电镜下, 染毒组胎盘绒毛中可见有膜包裹的致密体及合体细胞滋养层细胞内线粒体有不同程度的空泡变和嵴断裂; ICP-MS检测: 孕鼠血清铈的含量随染毒剂量的增加而递增, 染毒组胎儿羊水和孕鼠血清中稀土总量, 只有20 mg·kg-1组与对照组相比有显著增加, 其余各组均无显著差异. 胚胎组织提取液中各组的稀土总含量没有变化. 由此得出结论: 胎盘膜对混合稀土常乐进入胚体有很大的限制作用, 但是, 当混合稀土常乐在胎盘膜中积累增加到一定程度时, 可少量透过胎盘屏障, 进入胚体.     

光谱法比较喜树碱与溶菌酶、过氧化氢酶的相互作用

采用紫外可见吸收、红外、荧光等多种光谱学方法研究了抗癌药物喜树碱和溶菌酶及过氧化氢酶两种蛋白之间的相互作用,结果表明,喜树碱与之均形成基态复合物并引起蛋白内源荧光猝灭。通过计算确定了喜树碱和蛋白相互作用的结合常数、结合位点数、主要作用力类型以及与蛋白中色氨酸的结合距离。喜树碱对过氧化氢酶具有较高的结合能力,这主要是由于喜树碱不仅与过氧化氢酶中的色氨酸存在相互作用,也与酶中的酪氨酸及血红素产生相互作用。喜树碱的存在可引起蛋白构象发生变化,使α-螺旋二级结构减少。     

环腺苷二磷酸核糖（cADPR）的化学与生物学研究

通过立体选择环化βNAD实现了cADPR的生物模拟合成,并用这一方法合成了一系列cADPR类似物。类似物之一,cATP在鼠脑微粒体中释放Ca~(2 )的能力比cADPR强25倍。Aplysia环合酶和NAD酶皆可环合NADP~ 而生成。cADPRP。cADPRP调节Ca~(2 )释放的能力比cADPR强2倍。用亲和柱方法,从鼠脑中分离得到了cADPR结合蛋白(36kDa)和cADPRP结合蛋白(40kDa)。     

微量元素的解毒作用

微量元素锌和铜能够诱导肝、脑、肾合成金属硫蛋白（MT）。在胎儿期，几乎所有人体组织内均含有丰富的MT。成人期肝组织中的MT明显减少，脑肾中则很难测得，但都保存合成MT的能力。每分子MT蛋白可结合7～12个金属离子。     

Abtrennung und radiochemische Bestimmung geringer Mengen Seltener Erden in extraterrestrischem Material

The detection limits in neutron activation analysis are up to the standards of extraterrestrical matter analysis. Instrumental analysis is possible only after a group separation of the rare earth elements. The measurements requires a 26 day decay period. If results are desired within a shorter time interval the individual rare earth elements have to be separated. Gas chromatography and electrophoresis were applied in this work. Gas chromatography of metal chelates using radioactive reagents with high specific activity significantly improves the detection limits. The gas-chromatographic separations, however, should be only regarded as model experiments. The experimental results were obtained much faster (within 12 h) by applying high voltage electrophoresis of rare earth elements. Because of the excellent separation, the rare earth elements can be determined by automatic β-liquid scintillation spectrometry with high counting yields.     

双金属氰化物/稀土配合物催化二氧化碳和环氧丙烷的共聚合

使用双金属氰化物/稀土配合物复合催化剂催化二氧化碳和环氧丙烷共聚合,其催化效率比双金属氰化物催化剂有显著提高,得到了数均相对分子质量大于1.0×105的聚合物。研究了复合催化剂的组成(如稀土的种类、稀土与锌的比例(Ln/Zn)、稀土配合物中酸根离子的酸性等)对共聚反应的影响,同时研究了反应体系的压力及反应时间对催化活性的影响。采用Y(CCl3COO)3稀土金属配合物有利于共聚反应的进行。当n(Y)/n(Zn)=6、聚合4 h后,其催化活性比单纯的双金属氰化物提高了31.5%,聚合物的相对分子质量则没有太大变化,而副产物碳酸丙烯酯的质量分数低于2%,而在该温度下单独采用稀土三元催化剂时副产物碳酸丙烯酯的生成量通常在10%以上。聚合物中碳酸酯含量低于双金属氰化物的催化产物,说明稀土配合物只是起到活化金属与环氧丙烷配位的作用,没有提高共聚物的碳酸酯含量,整个共聚合反应依然遵循双金属氰化物催化的共聚反应机理。     

Concentration of all rare earth impurities of cerium sub-group rare earth matrices

The separability of all rare earth impurities from cerium sub-group matrices was investigated. It was found that anion exchange chromatography carried out with aqueous methanol solutions of nitrates provides a useful method for the concentration of all rare earth impurities in neodymium and gadolinium matrices. The concentrate of the impurities can be processed further as required by the method chosen for their analytical determination.     

负载稀土型酸活化膨润土的酯化催化活性

负载稀土型酸活化膨润土的酯化催化活性李永绣，冯天泽，胡平贵，何小彬，辜子英，廖荣辉（南昌大学化学系南昌３３００４７）关键词稀土，膨润土，催化酯化可用稀土、膨润土单独作酯化催化剂，但活性不高［１～３］。本文将稀土用离子交换的方法负载到酸活化膨润土中，寻...     

RING OPENING POLYMERIZATION OF PROPYLENE SULFIDE BY RARE EARTH COORDINATION CATALYSTS*

Ring opening polymerization of propylene sulfide using rare earth coordination catalysts has been investigated for the first time. It has been found that trinary rare earth coordination catslysts composed of rare earth compounds of phosphonate, naphthenate or acetylacetonate, trialkyl sluminum and water are effective catalysts for the polymerization of propylene sulfide. The polymerization in toluene is a homogeneous reaction. High molecular weight as high as several million poly(propylene sulfide) with high yield can be prepared by these catalysts. Kinetic studies showed that the polymerization rate is of first order with respect to both monomer concentration and catalyst concentration. The activation energy of the polymerization reaction is 61.4 k fJ/mol. The structure of the polymers so obtained has also been characterized by ~(13)C NMR spectroscopy, X-ray diffraction, gel permeation chromatography and differential scanning calorimetry.     

磷酸三丁酯萃淋树脂色层分离电感耦合等离子体质谱法测定富稀土样中微量铀和钍

研究了磷酸三丁酯萃淋树脂色层分离,电感耦合等离子体质谱法测定富稀土样中微量铀、钍的方法。样品经消解后,以磷酸三丁酯萃淋树脂为固定相、8 mol/L硝酸为流动相过柱分离,样品中的大部分稀土元素随流动相流出,而铀和钍则被固定相吸附,用去离子水洗脱后,再用电感耦合等离子体质谱仪测定。铀、钍的检出限分别为0.06,0.16μg/L,测定结果的相对标准偏差均小于10%(n=5),加标回收率为98%~105%。对稀土矿石标准物质进行测定,测定值与推荐值相符。该法操作简便,测定结果可靠,适于富稀土样中微量铀、钍的测定。     

Cation exchange separation of 16 rare earth metals by microscale high-performance liquid chromatography

The separation of rare earth metals has been studied with a micro-column of 0.5 mm i.d.×75 mm length, packed with TSK LS-212 high-performance cation exchange resin 16 rare earth metals were separated within 38 min, using only 304 μl of 0.4M α-hydroxyisobutyric acid solution adjusted to pH 3.1–6.0 with ammonia solution as gradient carrier solution. The gradient elution was successfully performed by applying a new technique developed for microscale liquid chromatography. Studies on micro-high-performance liquid chromatography, VII.     

Analysis of wines by ICP-MS: Is the pattern of the rare earth elements a reliable fingerprint for the provenance?

In a comparative analysis of young and finished product wines by semi-quantitative ICP-MS, a striking difference was observed: finished products exhibited significant concentrations of the rare earth elements whereas the concentrations in young wines which had not been subdued to any treatment after their initial preparation from the grapes were below the determination limits with a quadrupole instrument and could only be determined with a magnetic field instrument operated at a low mass resolution (R = 300). The reason was found in contamination from bentonites as usually applied for the purification of wines from tarnishing components such as proteins. Therefore, bentonites of different origin were extracted with a reference wine, and an increase of the rare earth element concentrations by more than one order of magnitude was observed in the extracts. The investigation leads to the conclusion that the concentration pattern of the rare earth elements can be strongly affected by the wine producing process and therefore is not generally suitable as a fingerprint for the provenance of wines.     

Rare earth element abundances and distribution patterns in plant materials

Eight out of the fourteen rare earth elements were estimated from the leaves ofPelthophorum pterocarpum, the leaves and roots ofImpatiens balsamina, and the soils from four sampling sites by instrumental neutron activation analysis. The chondrite normalized rare earth element abundances and distribution patterns in the plant materials were found to be significantly correlated to the abundances of the rare earth elements occurring in the soils. The extent of accumulation of the rare earth elements in some plant materials was also govemed by the age of the plants and the plant organs.