A W-band Electron Nuclear Double Resonance study of single crystals of N-14 and N-15 azurin
A W-band Electron Nuclear Double Resonance study of single crystals of N-14 and N-15 azurin
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DOI：
10.1021/ja962076u
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发表时间：
1996-12-04
影响因子：
15
通讯作者：
Messerschmidt, A
中科院分区：
文献类型：
--
作者：
Coremans, JWA;Poluektov, OG;Messerschmidt, A
我们报告了蓝铜蛋白天青蛋白及其完全富含 N-15 的类似物的单晶在 95 GHz 和 1.2 K 下的脉冲电子核双共振 (ENDOR) 实验。描述了氮 ENDOR 谱及其随晶体磁场方向的变化，并且表明可以区分五个遥远氮的贡献。对于铜配体组氨酸-46 和-117 的远程氮，提出并讨论了与铜位点结构和不成对电子波函数的扩展相关的完整超精细和四极张量。除了这些原子核之外，ENDOR 光谱中还出现了三个主链氮，并报告了它们的超精细张量。主链氮之一涉及半胱氨酸 112；其他的暂定为组氨酸-46 和甘氨酸-45。发现氧化天青蛋白的不成对电子的波函数在铜配体和部分蛋白质骨架上被涂抹。
We report pulsed Electron-Nuclear-DOuble-Resonance (ENDOR) experiments at 95 GHz and 1.2 K of single crystals of the blue-copper protein azurin and its fully N-15-enriched analogue. The nitrogen ENDOR spectra and their variation with the orientation of the magnetic field with respect to the crystals are described, and it is shown that contributions of five distant nitrogens may be distinguished. For the remote nitrogens of the copper ligands histidines-46 and -117 complete hyperfine and quadrupole tensors are presented and discussed in relation to the structure of the copper site and the extension of the wave function of the unpaired electron. Besides these nuclei three backbone nitrogens show up in the ENDOR spectra, and their hyperfine tensors are reported. One of the backbone nitrogens concerns that of cysteine-112; the others are tentatively assigned to histidine-46 and glycine-45. The wave function of the unpaired electron of oxidized azurin is found to be smeared out over both the copper ligands and parts of the protein backbone.