钼氧转移酶活性端配位场的仿生合成与研究

【作者】 娄福艳；

【导师】 鲁晓明；

【作者基本信息】 首都师范大学 ， 物理化学， 2005， 硕士

【摘要】 钼是动植物及人体所必需的微量生命元素,对生物体内的氮、硫、碳的代谢起重要的作用。微量元素钼进入生命体内后,主要以两种方式参与物质的代谢过程:一是以无机盐的方式,与其他营养物质相互络合;二是作为钼酶的重要组分—钼辅助因子,参与许多生化反应。钼在生物体内主要与蛋白结合,构成含钼酶的辅助因子,简称Mo-co。它能与各种酶的底物和抑制剂相结合。自上世纪50年代以来,研究发现除固氮酶以外,生物体内还存在另一类含有金属钼成分的酶,即钼氧转移酶,包括黄嘌呤氧化酶、硝酸盐还原酶、亚硫酸盐氧化酶和醛氧化酶等。这些酶与碳水化合物、脂肪、蛋白质、含硫氨基酸、核酸（DNA和RNA）及铁蛋白中铁的代谢密切相关。 由于蛋白质极其敏感和脆弱,在进行酶处理培养晶体的过程中可能引起钼酶活性因子的结构变化,从而使测定结果出现偏差。至今人们对钼酶中钼原子的配位环境了解得仍不够透彻。因此,对含有钼—硫（氮、氧）键配合物的合成、性质表征并对金属中心的结构、价态变化做进一步的研究,可望为探讨钼酶的结构及生物功能提供有用的信息。 1 以含有邻位取代基的邻苯二酚为配体,在甲醇乙腈混合溶剂中与（n-Bu₄N₄）₄[Mo₈O₂₆]反应,分别向体系中加入乙二胺、1,2-丙二胺和1,3-丙二胺,得到三种具有手性八面体构型阴离子的单核钼配合物,测得了晶体结构,进行了UV-VIS和EPR研究。该类酶的EPR信号与牛奶中的黄质氧化酶呈相似性,UV-VIS图谱与和鸡肝中的黄嘌呤去氢酶呈现相似性。 2 以2,3-二羟基萘为配体,在甲醇乙腈混合溶剂中与钼酸钠反应,加入乙二胺时,得到钠原子也参与配位的单核一维钼配合物;加入1,3-丙二胺时,得到与前述类似的具有手性八面体构型阴离子的单核钼配合物;加入1,2-N丙二胺时,没有得到配合物。对两种配合物进行了结构测定和UV-VIS研究,对后一种配合更多还原

【Abstract】 Molybdenum is an essential trace mineral that plays intimate roles in the global cycles of nitrate, carbon, and sulfur. It takes two forms when participated in the element metabolism, one is as inorganic salt and composed with nutrition, the other is as the cofacter of molybdeumenzy and takes part in many biochemistry reaction. Since last century 50 s the research shows that there is another kind of enzyme containing molybdenum except for nitrogen enzyme, which include xanthenes oxidase, nitrate reductase , sulfite oxidase and aldehyde oxidoreductase et al. Those molybdeumenzy have important influence upon the metabolism of carbohydrate, fat, protein, sulfamino acid, nucleic acid （DNA and RNA）, and iron in iron albumen.The active site structure of the molybdenum oxotransferase is likely to change during foster the molybdenumenzyme crystal because of the sensitivity and friability of the protein, which can make the result warp. There is still much to know about the surroundings of the molybdenum center. So the syntheses of the Mo-S （O/N） complexes and the researches of the structure and electron transfer of the molybdenum center can provide useful information for the crystal structure and activities studies of the molybdenumenzyme.1 Three different complexes were synthesized by the reaction of (n-Bu₄N_{4 4}[Mo₈O₂6] with catechol in the mixed solvent of CH₃OH CH₃CN, with NH₂CH₂CH₂NH₂, NH₂CH₂CHNH₂CH₃, and NH₂CH₂CH₂CH₂NH₂ added, and structurally characterized by x-ray diffraction. The crystal structure result shows that the mononuclear anionic unit of the three complexes displayed the same cis-dioxo fashion with pseudo-octahedral [MoO₆] coordination geometry. But the three complexes have different crystal figure, stability and anti-cancer activity. Those complexes show the similar EPR signals with xanthenes oxidase in milk and semblable UV-VIS signals with xanthenes dehydrogenase in chicken liver.2 2,3-dihydroxynaphthalene was chosen to react with Na₂MoO₄ in the mixedsolvent of CH₃OH, CH₃CN, with NH₂CH₂CH₂NH₂, NH₂CH₂CHNH₂CH₃, and NH₂CH₂CH₂CH₂NH₂ added, and two different molybdenum complexes were synthesized. When NH₂CH₂CH₂NH₂ was added to the mixed solvent, one-dimension mononuclear molybdenum complex was synthesized and the Na was also participated in it. The mononuclear molybdenum complex with the same anionic structure as before was synthesized when NH₂CH₂CH₂CH₂NH₂ was added, also when NH₂CH₂CHNH₂CH₃ added nothing was got from the solvent. The two complexes was structurally characterized by x-ray diffraction and researched with UV-VIS, also the NMR studies was taken on the later complex.3 2-hydroxypyrimidine and 2-anminothiophenol were chosen as ligand in the mixed solvent of CH₃OH and dichloromethane, and two compounds were synthesized and the IR studies shows that there are characteristic absorbed peak in about 900cm^-1, which is the character of molybdenum complex with pseudo-octahedral coordination geometry. The o-phenylenediamine was also chosen as N donor ligand to react with Na₂MoO₄ in H₂O and phenazine- 2,3-diamine with nut-brown of o-phenylenediamine dimmer was synthesized at the same time with acid added. Their crystal structures were determined by X-ray diffraction and researched with UV-VIS, IR, and fluorescence spectrophotometer, also the possible mechanism was discussed.更多还原