BIOLOGICAL METAL CLUSTERS BIOPHYSICAL & MODEL STUDIES

X射线吸收光谱法对于 表征金属蛋白和不稳定的 无机物种 在我们最近两次的EXAFS实验中， 在一九九七年十月至一九九八年六月期间， 结果（a）膜结合烷烃羟化酶AlkB在两个 还原态和氧化态，（B）合成过氧化铁和高价铁 铁物种相关的氧活化机制的 非血红素铁酶，（c）与Wilson相关的铜蛋白 疾病 氧化和还原AlkB的XAS研究表明， 活性部位的二铁中心有一个富含组氨酸的配体 环境，这是对比的羧酸盐丰富的网站， 可溶性二铁酶MMO和RNR。 这也表明了 氧化AlkB中的羟基桥代替提出的氧代桥 穆斯堡尔的结果 在我们努力模拟中间物种的过程中， 非血红素铁酶，我们已经获得了EXAFS数据上的一个 铁（III）-过氧中间体，并能够观察到短的Fe-N/O 在1.8 E键，推测与Fe-过氧键。 数据 也采取和分析双（μ-氧代）高价二铁 复合物，作为模型的中间体Q在MMO和X在 RNR。 我们对威尔逊病蛋白的初步分析表明 Cu（I）中心可能与Cys和 他的残留物，一种与之不同的配位环境， 铜分子伴侣Atx 1，有一些序列， 同源性

X-ray absorption spectroscopy has been very useful for characterizing the structures of metalloproteins and unstable inorganic species. In our last two runs of the EXAFS experiments in NSLS from October 1997 to June 1998, we have obtained significant results on (a) the membrane-bound alkane hydroxylase AlkB in both reduced and oxidized states, (b) synthetic iron peroxo and high valent iron species relevant to the oxygen activation mechanism of the nonheme iron enzymes, (c) a copper protein associated with Wilson disease. The XAS studies of oxidized and reduced AlkB indicates that diiron centers in the active site have a histidine-rich ligand environment which is contrast to the carboxylate-rich sites of the soluble diiron enzymes MMO and RNR. It also suggests the presence of a hydroxo bridge in oxidized AlkB instead of the oxo bridge proposed from Mvssbauer results. In our effort to model intermediate species of nonheme iron enzymes, we have obtained EXAFS data on an iron(III)-peroxo intermediate and are able to observe a short Fe-N/O bond at 1.8 E, presumably associated with the Fe-peroxo bond. Data was also taken and analyzed on bis(mu-oxo) high valent diiron complexes which serve as models of the intermediates Q in MMO and X in RNR. Our preliminary analysis of the Wilson disease protein suggests that the Cu(I) centers are likely to be coordinated by both Cys and His residues, a coordination environment which is distinct from that of the copper chaperone Atx1, to which there is some sequence homology.