化学模拟生物固氮——Ⅸ 铁钼辅基模型化合物的合成和性能表征

本文曾在全国化学摸拟生物固氮协作组领导小组扩大会议(昆明,1980,8)上宣读。[中文文摘]采用乙二醇基阴离子作为活插头(可通过水解除去的双配位螯形配位体),对前文提出的合成方法作了重要改进,以期所合成的铁钼辅基模型化合物中Mo~(Ⅳ(Ⅲ))第一配位界内两个不稳定的配位体处于相邻的位置,如厦门模型Ⅲ(或厦门模型Ⅱ)所要求。合成和重组活性评价结果,重组活性比使用乙腈等为活插头的提高2个数量级,化学催化活性和选择性接近于天然FeMo-co水平。[英文文摘]A significant improvement has been made to the method previously proposed[3] for synthesizing FeMo-co modeling compounds. With the use of ethylene glycolate anion as labilizable blocking agent (hydrolyzable bidentatc chelating ligand)to protect two neighboring coordination sites in the first coordination sphere of MoIV(III) of the synthesized FeMo-co modeling compound, an increase in reconstituted-nitrogenase activity of 2 orders of magnitude of the sample synthesized (as compared with the use of acetoni-trile or other monodentare ligands as bloeking agents)has been obtained.Catalytic activity and selectivity assays as well as preliminary characterization by EPR method have also been made

Evolution of a Model of Nitrogenase Active-center and Mechanism of Nitrogenase Gataivsis

参加本工作的还有:生物系曾定、许良树, 化学系庄秀治、张蕃贤、许志文等同志[中文摘要]本文提出固氮酶活性中心的骈联双座双立方烷原子簇结构的活性中心模型,[S~*Fe_3S_2~*(L)]Mo[(L’)S_2~*Fe_3S~*],其中L和L’代表两个可以移开的配位体,如N_2,-H,或-NH_3。这个模型是前阶段先后提出的骈联双座单立方烷原子簇结构模型,Fe_2S_2~*·Mo_2O_2,和骈联双座三立方烷原子簇结构模型,Fe_2S_c~*(L)(L’)Mo_2[S_3~*Fe_3S~*]_2,的又一次演进。这三个模型所共有的骈联双座原子簇结构特征和三核络合固氮方式,主要都是以固氮酶己知反应的十来种底物和抑制剂CO作为化学探针并应用络合催化原理而推断出来的。至于钼离子的价态和周围微环境,以及三核究竟是两钼一铁还是一钼两铁,则是参考最近国际上关于固氮酶的科学实验新成就而作出相应的修正和演进的。骈联双座双立方烷原子簇结构(含单钼)比较符合Orme-Johson和Munck等的顺磁共振和穆斯鲍尔谱实验结果,能说明比较多的实验事实。本文还扼要地讨论了固氮酶反应中ATP驱动的电子和质子传递机理。[英文摘要]A twin-sited-dicubane-type-cluster structural model of nitrogenase active-center, [S*Fe3S2*(L)]Mo[(L')S2*Fe3S*], has been proposed, L and L' being two labile ligands, such as N2, NH3, H,or H2O. This model is a logical evolution of the twin-sited-monocubane-type-clunter structural model, Fe2S2*Mo2O2, and the twin-sited-tricubane-type-cluster structural model, Fe2S2*(L)(L')Mo2[S3*Fe3S*]2, previously proposed by us. The twin-sited-cubane-type-duster structural feature common to all the three models and the end-on-plus-double-side-on coordination activation of N2,a-acetylenes,alkyl cyanides and isocyanides on the trinuclear active-center have been inferred mainly from the known reactions of nitrogenase with the various types of substrates and CO inhibitor regarded as chemical probes,and from the principles of coordination catalysis;whereas revision of previous models with regard to the micro-environments of each molybdenum ion and the nature of the triunclear active-center(whether it is 2Mo-1Fe,or 1Mo-2Fe)have been made by reference to recent progresses on nitrogenase research reported by many laboratories.The twin-sited-dicubane-type-cluster structural model(with 1 Mo111(IV))is in accord with the EPR and Moessbauer spectra of nitrogenase and FeMo-co recently obtained and interpreted by Orme-Johnson and Munck.It also gives better mechanistic explanations for the enzyme-catalyzed reactions of all the known nitrogenase substrates and the charac-teristic behavior of CO as a selective inhibitor of nitrogenase.A brief,further discussion of the mechanism of ATP-driven electron and proton transports is also given

Complexation of Fe_4S_4* Cluster with ATP and Coupling of Electron Transfer With ATP Hydrolysis

[英文摘要]Cathodic polarogram and electronic spectra of L4Fe4S4* cluster and L4Fe4S4*-ATP ( L≡-SCH2φ) as well as the relative amount ATP hydrolysis of the two systems-L4Fe4S4*-ATP-methylene blue and L4Fe4S4*-ATP were investigated. The results indicated that Fe4S4* could complex with ATP resulting in a redox-potensial shift to more negative value ( - 1.16V to -1.66V), thus increasing the electron donating tendency of L4Fe4S4*, and that when electron flowed out from the L4Fe4S4*·nATP complex, hydrolysis of the coordinated ATP was greatly promoted

Chemical Modeling of Biological Nitrogen FixationⅥ. Synthesis and Catalytic Activities of FeMo-co Modeling Compounds

[中文文摘]本文讨论了先前我们提出的固氨酶活性中心骈联双座双立方烷原子簇结构模型的一些特征。根据这一模型。设计了铁钼辅基模型化合物的合成方案,合成了三系列的铁钼辅基模型化合物,其Mo、S~*、Fe之比如同这一模型所要求的,为1:～6:6～8。由氯化物系列和柠檬酸盐进行配位体交换而得到的柠檬酸盐系列中的两个样品,在KBH_4还原C_2H_2为C_2H_4的反应中具有很高的催化活性(按每个Mo计算,转变数为20～30分~(-1))和选择性(91～95％),接近天然的铁钼辅基的水平,并在与Av突变种UW_(45)重组后,按Shah和Brill的方法测定,显示出明显的固氮酶活性。[英文文摘]Some features of the twin-sited dicubane-clurter structural model of nitrogenase active-center previously proposed by us are diseased. Based upon this model, a method for the synthesis of FeMo-co modeling compounds has been designed.Three series of FeMo-co modeling compounds have been synthesized, with Mo : S*: Fe=l:-6 :6-8 as required by the model. Two samples of the citrate series, obtained by ligand exchange of the chioridc series with citrate, have been found to exhibit very high catalytic activity (tur-over number per Mo:20~30min-1)and selectivity (92-95%C2H4),approaching that of FeMo-co,in the reduction of C2H4 to C2H4 by KBH4,and to show a certain well-confirmed nitrogenase activity as assayed by Shah and Bill's method after reconstitution with Av mutant UW45

A experimental research on biomechanical properties of iris tissue of human being

利用我们创建的将瞳孔水密缝合后，模拟眼内前后房压强差，对虹膜整体进行加压的实验方法，对人眼虹膜的力学特性进行了实验研究。结果表明：人眼虹膜是典型的粘弹性物质；面积模量与前后房压强差之间基本成线性关系。实验结果可为青光眼致盲机制解释和瞳孔阻滞力的估算提供参考

A experimental research on biomechanical properties of iris tissue of rabbits

利用我们创建的将兔眼蝉孔水密缝合后，模拟眼内前后房压强差，对虹膜整体进行加压的实验方法，对兔眼虹膜的力学特性进行了实验研究。结果表明：兔眼虹膜是典型的粘弹性物质；面积模量与前后方压强差之间基本成线性关系。实验结果可为青光眼致盲机制解释和瞳孔阻滞力的估算提供参考

Influence of Ambient Pressure on Performance of a Deep-sea Hydraulic Manipulator

Deep-sea hydraulic manipulator is the most commonly used operation equipment for executing subsea operations in different applications. The increasing demands on underwater operational ease require the implementation of manipulator system which can maintain similar dynamic performance in different working conditions Considering the variations of seawater properties at different ocean depths, especially high hydrostatic pressure in deep-sea environment will make the kinematic viscosity of oil obviously increased, which has a significant influence on the performance of deep-sea hydraulic manipulator. The viscosity-pressure characteristics of working medium is tested. A detailed nonlinear mathematical model and related simulations considering the significant slender pipelines between valves and actuators due to the increased oil viscosity are conducted to analyze the ambient pressures against varying depths affecting the manipulator performance. The 115MPa online pressure experimental results indicate the joint response characteristics at different ambient pressures, which provides basis for response consistency control of deep-sea hydraulic manipulator