表面带负电荷氨基酸残基的突变对细胞色素b5与细胞色素c结合和识别的影响

利用核磁共振方法研究表面带不同负电荷氨基酸残基突变后的细胞色素b₅与细胞色素c的结合与识别.结果表明,静电作用在细胞色素b₅与细胞色素c的结合过程中有着重要的贡献,而且这些静电贡献在一定程度上具有累加性,E48的贡献略大于E44.同时还证明Browniandynamicssimulations优化出的Glu48-Lys13,Glu56-Lys₈₇,Asp60-Lys86和heme6-propionate-Tml₇₂(细胞色素b₅的残基排在前面)的结合方式在溶液中的确存在.细胞色素b₅突变体(E48,E56/A,D60/A)及[Cr(oxalate)₃]^3-对细胞色素c的表面结合竞争实验表明,细胞色素c表面结合区Site仍然同细胞色素b₅突变体(E48,E56/A,D60/A)有结合作用,只是结合强度上相对于野生细胞色素b₅同细胞色素c的结合有所降低.这表明除上述的Brownian dynamics simulations模型外,尚有其它如Salemme模型等的结合方式,这也揭示出细胞色素b₅和细胞色素c之间的结合是比较动态的.     

Studies on Cytochrome c Modified by [PtdienNO_3]Cl

For the first time, [PtdienNO_3]Cl was used as a stable reagent to modify ferricytochrome c and the reaction products were separated and purified with the CM-52 cation exchange chromatography. Five components were obtained, corresponding to the native cytochrome c single-labeled, dual-labeled, and triple-labeled derivatives as shown by the analysis of the molar ratio of the two metal atoms (Pt and Fe). The reduction potentials of these proteins were measured by differential pulse voltammetry. His-33 and Trp-59 were identified by~1HNMR as the binding sites of the platinum complex in the modified cytochrome c derivatives. Trp-59 was a conserved amino acid connected with the heme through hydrogen bond, which had not been modified by other transition metal complexes. The platinummodified cytochrome c derivatives might be valuable in exploring the role of the aromatic amino acids, especially Trp-59, in electron transfer.     

亚相金属离子与两亲配体LB膜相互作用的研究

The complex formation of 2-hexadecylcarbamoyl-8-hydroxyquinoline(HHQ) monolayers at the air/water interface by reaction with metal ions from the subphase was investigated using X-ray photoelectron spectroscopy. The formation of HHQ-metal complexes leads to the appearance of new peaks assigned to the metal ions. The information on stoichimoetry provided by XPS indicated that a metal ion is coordinated by two HHQ molecules for La3+ and Cd2+ ions, but by one HHQ molecule for Mn2+ and Ni2+ ions.     

我国络合物化学三十年

络合物化学的研究已有一百多年历史,但络合物化学的迅猛发展还只是近三十多年的事。现代络合物化学的研究领域已远远超出纯无机化学的范围,它涉及有机化学、催化机理、物质结构、化学键理论以及生命现象中一系列与金属离子有关的重要问题。络合物化学已广泛应用于稀有和有色金属的分离提取,核燃料和反应堆材料的生产,石油化工中络合催化以及电镀、印染、鞣革等国民经济中许多工业部门。     

Cu, Zn─SOD酶模型化合物催化O2－歧化作用的研究

为了解Ｃｕ，Ｚｎ－ＳＯＤ酶结构和功能关系，尤其是Ｃｕ周围配位构型对催化Ｏ＾－２歧化活性的影响，本文用ＮＢＴ法测定了Ｃｕ，Ｚｎ－ＳＯＤ酶和两个Ｃｕ－ｉｍ－Ｚｎ模型配合及相应单核配合物催化Ｏ＾＿２歧化的活性，结果表明不同咪唑桥联方式和不同配位构型的化合物催化Ｏ＾－２歧化的活性明显不同。     

咪唑键合细胞色素C的核磁共振共振研究

我们用^1HNMR双共振技术测定了在pH=7.04,温度303-319K范围内咪唑键合氧化型细胞色素C的平衡常数,从Van'tHoff和Arrhenius方程得到键合的热力学常数△H=48.5kj·mol^-1,△S°=184J·mol^-1·K^-1和活化能E~a=159kj·mol^-1,并与其它血红素蛋白和模型化合物的热力学常数作了比较和讨论.用饱和转移法归属了cytc·Im的血红素环上甲基峰,首次用NMR方法确证咪唑在与氧化型cytc反应中取代了轴向Met80,形成新的Fe-N键.     

六氯合铂酸钾与金属硫蛋白的体外反应

本文报道了K₂PtCl₆与兔肝Zn₇MT-Ⅱ和apoMT-Ⅱ的反应包含一个氧化还原反应和一个取代反应。通过紫外可见光谱、园二向色谱、柱层析和X-光电子能谱研究了该反应的性质、铂在反应产物中的键合位置和氧化态。金属硫蛋白(MT)被氧化成单体、双聚和多聚产物，其中含有分子间和分子内CyS-SCy二硫键。Pt(Ⅳ)被还原成Pt(Ⅱ)然后键合于产物中。随着K₂PtCl₆与MT的反应摩尔比和反应时间的增加，键合于产物中的Pt(Ⅱ)的计量数增加而蛋白中所含Zn(Ⅱ)的量减少。当Zn₇MT与4和超过10摩尔的K₂PtCl₆反应时，分别得到了Pt₄Zn₄MT和Pt₈MT。当apoMT与7及超过25倍的K₂PtCl₆在pH 2条件下反应时，分别得到了Pt₇MT和Pt₁₅MT。动力学数据表明K₂PtCl₆与apoMT的反应比与Zn₇MT的反应快。     

N，N’－双［（1－苯基－3－甲基－5－氧－4－吡唑啉基）亚苄基］乙二亚胺萃取钯的机理及钯－铂体系中钯的选择性萃取

本文首次报道了标题试剂Ｈ２Ａ对钯的萃取行为，确定了萃取物的组成，讨论了萃取机理，算出了萃取平衡常数．通过化学分析、红外及拉曼光谱、紫外光谱，研究得出了萃合物的结构，并且实现了Ｈ２Ａ从钯－铂混合溶液中选择性萃取钯．     

A MODEL STUDY ON MODE OF BONDING OF CISPLATIN WITH DNA

The interaction of cis-[Pt(NK_3)_2Cl_2] with nucleosides, as constituents of DNA, was studled by spectrophotometric, ~(13)C NMR and CNDO/2 methods. The apparent stability constants of the complexes formed and the initial rate of formation were determined. The sites of binding of nucleoside (or nucleotide) with Cisplatin were ascertained and the electronic structure of the model coordination compounds of Cisplatin and guanine was calculated by MO approach. On the basis of the obtained results, the mechanism of the antitumour action of Cisplatin was discussed, and a new possible mode of bonding of Cisplatin with DNA was proposed.