E COLI: TELLUROMETHIONINE IN STRUCTURAL BIOCHEMISTRY

SIR提供L-[B_2H2]色氨酸100 mg和L-[4‘_17 O]酪氨酸酪氨酸自由基存在于各种酶系统中 包括核苷酸，还原酶，前列腺素合成酶， Potosystein 111和半乳糖氧化酶。自旋密度分布 可能会被环境因素改变，其中一些因素可能是关键的 对于酶结合自由基的作用。我们已经卷入了 用EPR光谱对这些自由基进行表征 确定自旋密度。最近的研究表明，在 核糖核苷酸中酪氨酸的苯酚氧位 还原酶，在光系统H和酪氨酸的化学模型中。 这项研究旨在阐明特定的蛋白质-自由基相互作用 对酶起作用的物质。我们建议访问自旋 用[4‘-170]酪氨酸标记的酚氧密度。通过 与Britt-Marie Sj6berg教授的斯德哥尔摩小组合作，我们 得到了~(70)T标记酪氨酸自由基的EPR谱。 核糖核苷酸还原酶，并寻求获得互补模型 和光系统H数据。模型17 O标记的酪氨酸自由基将是 由我们开发的紫外线技术产生[Barry等人，1990 JBC265,20139-20141)。17个O标记的酪氨酸将被加入 利用营养缺陷型转化蓝藻聚球藻 我们已经描述过的情况(Barry和Babcock，1987 程序娜塔莉。阿卡德。SCI。美国，84,7099-7103)。电子顺磁共振波谱将 就像在这些早期研究中一样。细菌的活性部位 甲胺脱氢酶含有一种新的氧化还原修复基团 色氨酸色氨酸对苯二酚由两种色氨酸组成 还钱。氢化色氨酸将被用来探测自旋 辅因子在色尼奎酮中的密度分布。

The SIR provided L-[B_2 H2]Tryptophan; 100mg and L-[4' _17 O]Tyrosine Tyrosine radicals occur in a variety of enzyme systems including ribonucleotide, reductase, prostaglandin synthase, Photosystern 111, and galactose oxidase. Spin density distributions can be altered by environment factors, some of which may be critical for the function of enzyme-bound radicals. We have been involved in characterizing these radicals by EPR spectroscopy in order to determine spin-density. Recent work suggests substantial variation in r at the phenol oxygen position in tyrosines in ribonucleotide reductase, in Photosystem H, and in a chemical model of tyrosine. This study aims at elucidating particular protein-radical interactions that contribute to enzyme function. We propose to access the spin density at the phenolic oxygen by labeling with [4'- 170]tyrosine. By collaborating with the Stockholm group of Prof Britt-Marie Sj6berg, we have obtained the EPR spectrum of the '70_ labeled tyrosine radical in ribonucleotide reductase, and we seek to obtain complementary model and Photosystem H data. Model 17 O-labeled tyrosine radicals will be generated by the UV techniques we have developed [Barry et al., 1990 JBC 265, 20139-20141). 17 O-labeled tyrosine will be incorporated into the cyanobacterium Synechocystis by using the auxotrophic condition that we have already described (Barry and Babcock, 1987 Proc. Natl. Acad. Sci. USA, 84, 7099-7103). EPR spectroscopy will be done as in these earlier studies. The active site of bacterial methylamine dehydrogenases contains a novel redox prosthetic group tryptophan tryptophanyl quinone that is made up of two tryptophan redidues. P-Deuterated tryptophan will be used to probe the spin density distribution in the serniquinone fon-n of the cofactor.