ELECTRON TRANSFER PATHWAYS/BLUE COPPER PROTEINS

反硝化细菌是管理废物的重要试剂， 是大气中一氧化氮的来源 其中一个电子 硝酸盐最终通过NO2转化为N2的转移途径 和NO，利用特别有效的反硝化细菌 粪产碱菌，菌株S-6，含铜亚硝酸盐还原酶， 和一种蓝色蛋白质，它在正常情况下作为 将电子转移到亚硝酸盐还原酶，也可以作为 在O2存在下的抑制剂 一种叫做“Achromobacter cycloclastes”的微生物 在其脱氮途径中也含有类似的一对分子。 我们已经确定了化学序列和蛋白质折叠的 蓝蛋白（铜氧还蛋白）。粪便，并计划继续 阐明差异的高分辨率结构细节 在分子的两种氧化态之间。 结构是这样的 一个合理的假设之间的特异性起源 蓝蛋白和它的亚硝酸还原酶存在于一个C-末端螺旋的 蓝色蛋白质，看起来也很容易被去除， 蛋白水解 这一假设将通过执行 切割和测试剩余的相互作用特异性。 这些蓝铜蛋白是专门用来结合 McMillin和Engeseth已经通过加热证明了铜的存在 对相关蓝铜蛋白，天青蛋白， 除铜外的金属结合，并且没有任何金属。 我们计划检查 通过X射线衍射方法， 为了深入了解金属在蛋白质中的作用， 完整 最后，为了提供关于铜氧还蛋白1的伴侣的信息，我们 计划确定含铜亚硝酸还原酶的结构 来自于“无色杆菌” 这将揭示一种新的 这种铜蛋白质，以及允许我们检查的细节， 它与其铜氧还蛋白（A.粪菌1）， 在特定的电子转移链中的两个伙伴。

Denitrifying bacteria are important agents in managing waste, as well as being a source of nitric oxide in the atmosphere. One of the electron transfer pathways in which nitrates are converted eventually to N2 via NO2 and NO, utilizes, for the particularly potent denitrifying bacteria Alcaligenes faecalis, Strain S-6, a copper containing nitrite reductase, and a blue protein which which while normally acting as the agent which transfers an electron to the nitrite reductase, can also act as an inhibitor in the presence of O2. The organism "Achromobacter cycloclastes" also contains a similar pair of molecules in its denitrification pathway. We have determined the chemical sequence and the protein folding of the blue protein (cupredoxin) from A. faecalis, and plan to continue to elucidate the structural details at high resolution of the differences between the two oxidation states of the molecule. The structure is such that a plausible hypothesis for the origin of the specificity between the blue protein and its nitrite reductase resides in a C-terminal helix of the blue protein, which also looks as if could be easily removed proteolytically. This hypothesis will be tested by carrying out the cleavage and testing for remaining specificity of interaction. That these blue copper protein are specifically designed for binding just copper has been demonstrated by McMillin and Engeseth, by doing heat capacity measurements on the related blue copper protein, azurin, with metals other than copper bound, and without any metal. We plan to examine the structure of azurin without a copper, by X-ray diffraction methods, in order to gain insight into the role the metal plays in the protein integrity. Finally, in order to provide information on the partner of cupredoxin 1, we plan to determine the structure of the copper containing nitrite reductase from "Achromobacter cycloclastes". This will reveal the structure of a new kind of copper protein as well as allow us to examine the details of the interaction of it and its cupredoxin (a homolog of the A. faecalis one), two partners in a specific electron transfer chain.