Transferase Enzyme Catechol As Ligand Of Molybdenum Oxide, Biomimetic Synthesis, Characterization, And Nature Study

Molybdenum is an essential trace element that plays important roles in the global cycles of nitrate, sulfur, and phosphor. 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 reactions. Since last century 50's the research shows that there is another kind of enzyme containing molybdenum except for nitrogen enzyme, which includes xanthenes oxidase, nitrate reductase, Sulfite Oxidase and Aldehyde Oxidoreductase et al. Those molybdeumenzy had important influence upon the metabolism of carbohydrate, fat, protein, sulfamino acid, nucleic acid (DNA and RNA), and iron in iron albumen.Chiral octahedral molybdenum-containing complexes are active cofactor of biomemic molybdeumenzy. Being similar complex compare with cis-platinum, there provided with incising and identifying DNA and anticancer activity. So biomemic synthesis and biochemical mechanism study of active cofactor of molybdeumenzy attracted considerable attention.X-ray crystal analyses reveal that the cofacter of molybdeumenzy is composed of Mo atoms and S atoms of disulfulene. Polyphenols are antioxidants, which are known to influence bioavailability of metals in the body. In addition, metal-catechol complexes can exhibit interesting electronic effects associated with the variable metal and ligand charge distribution, due to the delicate balance in energy between the frontier quinine and metal orbitals and they are believed to be a model for the biological transport of iron and catechol/quinine related enzymes and biomolecules. In this thesis, a series of biomimetic complexes with catechol ligand of molybdeumenzy cofactor have been synthesized and characterized by IR, ¹HNMR, TEM, SEM, EPR, X-ray analyses. The main points are as follows:1 Five different complexes were synthesized by the reaction of tetra-butyl ammonium β-octamolybdate with catechol in the mixed solvent of CH₃OH, CH₃CN, with NH₂CH₂CH₂NH₂, NH₂CH₂CHNH₂CH₃, and NH₂CH₂CH₂CH₂NH₂ added differently, and structurally characterized by x-ray diffraction, IR, ¹HNMR, TEM, SEM and EPR.(a) Structural characterization by x-ray diffraction: The crystal structure results show that the mononuclear anionic unit of the three complexes displayed the same cis-dioxo fashion with pseudo-octahedral [MoO₆] coordination geometry. However, the five complexes have different crystal figure, stability and anti-cancer activity.(b) EPR studys: Those complexes show the similar EPR signals with xanthenes oxidase in milk and semblable UV-VIS signals with xanthenes dehydrogenase in chicken liver. In addition, some of the complexes have excellent anticancer activity.(c) NMR results: The NMR studies on the interaction of the complex 3 with ATP reveal that ¹H chemical shifts of 1,2-propanediamine and catechol with and without ATP exhibit distinct difference. The reduction of Mo(VI) to Mo(V) occurs when the complex 3 is dissolved in D₂O, and the Mo(V) is oxidized again when ATP solution is mixed with original solution , and the hydrolysis of the catechol ligand take places at mean time which were monitored by ¹H NMR.2 Catechol was chosen to react with Na₂MoO₄ in the mixed solvent of CH₃OH, CH₃CN, with NH₂CH₂CH₂NH₂, NH₂CH₂CHNH₂CH₃ added differently, and four different complexes were synthesized. When NH₂CH₂CH₂NH₂ added to the mixed solvent, two different complexes obtained in the same tube. One is the mononuclear molybdenum-containing complex with the same structure as before. The other is a two-dimension complex in which sodium coordinated with catechol but not contain molybdenum atom. One-dimension mononuclear molybdenum complex synthesized and the Na participated in it when NH₂CH₂CHNH₂CH₃ added. When NH₂CH₂CH₂CH₂NH₂ was added into the mixed solvent, we got a one dimension dichain dinuclear molybdenum complex which was bridged by sodium metal and 1.3-diaminopropane. The five complexes were structurally characterized by X-ray diffraction, SEM, TEM and NMRstudies were taken also.(a) Structural characterization by x-ray diffraction: The crystal structure results show that complex 6 consists of two NH₂CH₂CH₂NH₂ and a discrete molecular {Na₂(μ₂-(C₆H₆O₂)₂](C₆H₄OOH)₂} cluster. While in complex 8, Mo atoms are bridged by O-Na-O units constituting a one-dimensional (1D) infinite chain along the α-axis, and the neighboring chains are linked by van der vaals force and H-bonds. In complex 9, molybdenum atoms are bridged by two sodium and one 1.3-diaminopropane constituting a one dimension dichain structure, and the neighboring chains are linked by protonated 1.3-diaminopropane through hydrogen bonds..(b) The comparison of ¹³C NMR spectrum of the complex 7 in solid state with that in solution indicates that the rapid exchange between the bridging μ₂-(C₆H₆O₂) and terminal (C₆H₄OOH)^- ligands is presented in solution.