METAL SULFUR & METAL CARBOXYLATE SITES IN REDOX ENZYMES

生物系统中的电子转移和氧化， 生物体中各种底物的还原是 对生命维持过程至关重要。 多重 电子转移过程，虽然在自然界中不太频繁， 同样重要。 其中，第四名是： 光合作用中2 H2O氧化成O2， 固氮酶中N2还原为氨，以及亚硫酸盐还原为 亚硫酸盐和亚硝酸盐还原酶中硫化物和亚硝酸盐转化为氨 分别 在参与的酶中， 底物的氧化或羟基化是甲烷 单加氧酶，MMO。 这种酶能催化 甲烷在活性位点转化为甲醇，与细胞色素P- 450，不利用Fe-卟啉中心。 本建议涉及对下列问题的综合和研究： a）涉及多电子的金属酶的合成类似物 还原和B）在氧化中具有活性的非卟啉中心 和有机底物的羟基化。 具体而言： 的合成、结构、光谱性质和反应活性 Fe/M/S（M=Mo，W，V）和Fe/S团簇 作为固氮酶中Fe/M/S中心的合成类似物， 含钒或铁的交替固氮酶 钼。 本文还讨论了Fe/S团簇的新类型， 合成的被设计为模型的P-集群的 固氮酶 附加Fe/S的超分子组装 将合成簇作为活性位点的可能模型 亚硫酸盐和亚硝酸盐还原酶。 低聚络合物是已知的， 或被认为是，参与的过程，如氧化的 MMO（M =Fe）中CH 4转化为甲醇的反应和光合作用的影响。 将水氧化成O2（M-Mn）。 单体，混合配体 羧酸络合物也参与酶促氧化 例如儿茶酚官能团氧化成顺式粘康酸 以及苯丙氨酸的芳环羟基化为酪氨酸 通过与分子氧反应，（M =Fe）。 羧酸盐络合物 第一行元素将作为结构和反应性进行研究 催化氧化的酶中活性位点的模型 各种基材。

Electron transfer in biological systems and the oxidation and reduction of various substrates in living organisms are of fundamental importance to life sustaining processes. Multi- electron transfer processes, although less frequent in nature are of equally great importance. Included among the latter are: The 4e- oxidation of 2H20 to 02 in photosynthesis, the 6e- reductions of N2 to ammonia in nitrogenase, and the 6e- reduction of sulfite to sulfide and of nitrite to ammonia in sulfite and nitrite reductases respectively. Outstanding among the enzymes involved in the oxidation or hydroxylation of substrates is methane monooxygenase, MMO. This enzyme catalyzes the oxidation of methane to methanol at an active site that, unlike cytochrome P- 450, does not utilize an Fe-porphyrin center. This proposal is concerned with the synthesis and study of synthetic analogs for a) metalloenzymes involved in multielectron reduction and b) the non-porhyrin centers active in the oxidation and hydroxylation of organic substrates. Specifically: the synthesis, structures, spectroscopic properties and reactivities of Fe/M/S (M=mo, W, V) and Fe/S clusters are expected to serve as synthetic analogs for the Fe/M/S centers in the nitrogenases and alternate nitrogenases that contain vanadium or iron in place of molybdenum. The new types of Fe/S clusters that will be synthesized are designed as models for the P-clusters of nitrogenase. Supramolecular assemblies with appended Fe/S clusters will be synthesized as possible models for the active sites in sulfite and nitrite reductase. Oligomeric complexes are known, or believed to be, involved in processes such as the oxidation of CH4 to methanol in MMO (M =Fe) and the photosynthetic oxidation of water to 02(M -Mn). Monomeric, mixed-ligand carboxylate complexes also are involved in enzymatic oxidations such as the oxidation of the catechol function to cis muconic acid and the aromatic ring hydroxylation of phenylalanine to tyrosine via reaction with dioxygen, (M =Fe). Carboxylate complexes of first row elements will be studied as structure and reactivity models for the active sites in enzymes that catalyze the oxidation of various substrates.