Structure of the copper cluster in canine hepatic metallothionein using X-ray absorption spectroscopy.
Structure of the copper cluster in canine hepatic metallothionein using X-ray absorption spectroscopy.
复制标题
使用 X 射线吸收光谱分析犬肝金属硫蛋白中铜簇的结构。
DOI：
10.1021/bi00357a007
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发表时间：
1986
期刊：
影响因子：
2.9
通讯作者：
Peisach,J
中科院分区：
文献类型：
--
作者：
Freedman,JH;Powers,L;Peisach,J
分子药理学和分子生物学系，阿尔伯特·爱因斯坦医学院，布朗克斯，纽约10461和AT&T贝尔实验室，默里山，新泽西07974接收日期：1985年6月18日;修订版手册接收日期：1985年12月31日摘要：用X射线边谱和扩展X射线吸收精细结构（EXAFS）研究了犬肝溶酶体铜金属硫蛋白（LyCuLP）的金属结合位点。LyCuLP的/c-吸收边光谱与单价铜的配位一致。EXAFS数据的傅里叶变换显示了四个分辨的背散射原子壳层。从孤立壳层得到的相位和振幅函数与Cu-Cu，Cu-S和Cu-N模型化合物的相位和振幅函数之间的比较表明，每个铜与四个距离为2.27±0.02 μ m的硫原子配位。对外壳数据的分析表明，铜原子在2.74±0.05、3.32±0.05和3.88±0.05 μ m处反向散射。从EXAFS数据确定的原子间距离进行了比较，观察到的距离由X射线晶体学分析金刚烷类簇含有四个和五个铜原子和一个立方簇含有四个铜原子，结构上类似的4Fe-4S簇中的一些铁氧还蛋白。这些比较的结果表明，在LyCuLP中络合的铜被布置在金刚烷样簇中。1957年，Margoshes和Vallee从马肾皮质中分离出一种蛋白质，后来被命名为“金属硫蛋白”（Margoshes和Vallee，1957）。从那时起，这种蛋白质已经从其他哺乳动物、鱼类、无脊椎动物和真菌中分离出来（Kojima & Kági，1978，Nordberg & Kojima，1979）。金属硫蛋白是低分子量、可诱导的蛋白质，其结合多种金属，包括汞、金、铅、锌和铜（Winge等人，1975年，1981年）。金属硫蛋白的功能尚未完全了解，尽管它们被认为参与重金属的解毒（Kojima & Kági，1978），在其合成期间将金属捐赠给其他金属蛋白（Lerch，1980），以及维持组织中铜和锌的稳态水平（Evans，1973;布卢默& Lee，1978）。一些病理条件与铜的积累，以及金属硫蛋白水平的改变。这些包括威尔逊病（Evans等人，1973; Scheinberg和Sternlieb，1976）、门克斯病（Menkes等人，一九六二年; Riordan & Jolicoeur-Paquet，1982），和遗传性铜中毒，一种类似于威尔逊病的贝德灵顿梗的异常（Twedt等人，1979;约翰逊等人，1981年）。金属硫蛋白的金属结合能力为4-11摩尔金属/摩尔蛋白质（Winge等人，1981），与其高巯基含量有关。哺乳动物蛋白质中约30%的氨基酸残基是半胱氨酸（Lerch，1981）。
Departments of Molecular Pharmacology and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461, and AT&T Bell Laboratories, Murray Hill, New Jersey 07974 Received June 18, 1985; Revised Manuscript Received December 31, 1985 abstract: The metal binding site in the lysosomal copper metallothionein from canine liver (LyCuLP) was examined with X-ray edge and extended X-ray absorption fine structure (EXAFS) spectroscopies. The/c-absorption edge spectrum of LyCuLP was consistent with the coordination of univalent copper. The Fourier transform of the EXAFS data showed four resolved shells of backscattering atoms. Comparisons between the phase and amplitude functions derived from the isolated shells to those of Cu—Cu, Cu-S, and Cu-N model compounds showed that each copper was coordinated by four sulfur atoms at a distance of 2.27±0.02 Á. Analysis of the outer shell data indicated backscattering copper atoms at 2.74±0.05, 3.32±0.05, and 3.88±0.05 Á. Interatomic distances determined from the EXAFS data were compared to the distances observed by X-ray crystallographic analysis of adamantane-like clusters containing four and five copper atoms and a cubic cluster containing four copper atoms, structurally similar to the 4Fe-4S clusters in some ferredoxins. The results of these comparisons suggest that the copper complexed in LyCuLP is arranged in an adamantane-like cluster. The structure derived for this protein may be conservedin other copper metallothioneins.In 1957, Margoshes andVallee isolated a protein from equine renal cortex that was later named “metallothionein”(Mar-goshes & Vallee, 1957). Since that time, this protein has been isolated from other mammals, fish, invertebrates, and fungi (Kojima & Kági, 1978, Nordberg & Kojima, 1979). Metallothioneins are low molecular weight, inducible proteins that bind a variety of metals including mercury, gold, lead, zinc, and copper (Winge et al., 1975, 1981). The function of the metallothioneins is not completely understood, although they are believed to be involved in the detoxification of heavy metals (Kojima & Kági, 1978), the donation of metals to other metalloproteins during their synthesis (Lerch, 1980), and the maintenance of homeostatic levels of copper and zinc in tissue (Evans, 1973; Bloomer & Lee, 1978). Several pathological conditions are associated with the accumulation of copper, together with alterations in metallothionein levels. These include Wilson’s disease (Evans et al., 1973; Scheinberg & Sternlieb, 1976), Menkes’ disease (Menkes et al., 1962; Riordan & Jolicoeur-Paquet, 1982), and inherited copper toxicosis, an abnormality in Bedlington terriers similar to Wilson’s disease (Twedt et al., 1979; Johnson et al., 1981). The metal binding capacity of metallothionein, 4-11 mol of metal/mol of protein (Winge et al., 1981), is related to its high sulfhydryl content. Approximately 30% of the amino acid residues in the mammalian protein are cysteine (Lerch, 1981).