Azide binding to the trinuclear copper center in laccase and ascorbate oxidase.
Azide binding to the trinuclear copper center in laccase and ascorbate oxidase.
复制标题
叠氮化物与漆酶和抗坏血酸氧化酶中的三核铜中心结合。
DOI：
10.1046/j.1432-1327.1999.00898.x
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Daniella Goldfarb
中科院分区：
文献类型：
--
作者：
I. Gromov;A. Marchesini;O. Farver;Israel Pecht;Daniella Goldfarb
通过电子顺磁共振 (EPR) 和脉冲电子核双共振 (ENDOR) 光谱研究了叠氮化物与蓝色铜氧化酶漆酶和抗坏血酸氧化酶 (AO) 的结合。随着漆酶：叠氮化物摩尔比从 1:1 降低至 1:7，2 型 (T2) Cu(II) EPR 信号强度降低，并出现 g 约为 1.9 处的信号。温度和微波功率相关的 EPR 测量表明，该信号具有相对较短的弛豫时间，因此仅在 40 K 以下观察到。在 AO：叠氮化物 (1:7) 样品中发现了大约 1.97 g 的信号，具有类似的饱和特性。两种蛋白质中的 g < 2 信号被分配给 S = 1 偶极耦合 Cu(II) 对，由此叠氮化物结合破坏了 3 型 (T3) Cu(II) 对的反铁磁耦合。对 g < 2 信号位置的分析表明，漆酶中偶极耦合的 Cu(II) 对之间的距离比 AO 中的更短。 T2 Cu(II) 与 S = 1 Cu(II) 对的接近增强了其弛豫率，从而降低了其相对于天然蛋白质的信号强度。 T3 反铁磁耦合的破坏仅发生在部分蛋白质分子中，而在其余部分中观察到不同的叠氮化物结合模式。 AO 和具有叠氮化物 (1:7) 的漆酶的 130 K EPR 谱图，除了未受干扰的 T2 Cu(II) 信号外，还显示出 g 平行区域中的新特征，这些特征归因于蛋白质分子中受干扰的 T2，其中 T3 的反铁磁耦合尚未被破坏。虽然这些特征在 10 K 的 AO：叠氮化物样品中也很明显，但在 6-90 K 范围内测量的漆酶：叠氮化物样品的 EPR 光谱中不存在这些特征。此外，在 4.2 K 下对后者进行脉冲 ENDOR 测量，仅显示与 T2 Cu(II) 配位的 14N 组氨酸的 20 MHz 峰值强度降低，但没有解决任何可能表明叠氮化物的显着变化。与该离子结合。漆酶中低于 90 K 时缺乏 T2 Cu(II) 信号扰动可能是由于三核：叠氮化物复合物内耦合的温度依赖性。
Azide binding to the blue copper oxidases laccase and ascorbate oxidase (AO) was investigated by electron paramagnetic resonance (EPR) and pulsed electron-nuclear double resonance (ENDOR) spectroscopies. As the laccase : azide molar ratio decreases from 1:1 to 1:7, the intensity of the type 2 (T2) Cu(II) EPR signal decreases and a signal at g approximately 1.9 appears. Temperature and microwave power dependent EPR measurements showed that this signal has a relatively short relaxation time and is therefore observed only below 40 K. A g approximately 1.97 signal, with similar saturation characteristics was found in the AO : azide (1:7) sample. The g < 2 signals in both proteins are assigned to an S = 1 dipolar coupled Cu(II) pair whereby the azide binding disrupts the anti-ferromagnetic coupling of the type 3 (T3) Cu(II) pair. Analysis of the position of the g < 2 signals suggests that the distance between the dipolar coupled Cu(II) pair is shorter in laccase than in AO. The proximity of T2 Cu(II) to the S = 1 Cu(II) pair enhances its relaxation rate, reducing its signal intensity relative to that of native protein. The disruption of the T3 anti-ferromagnetic coupling occurs only in part of the protein molecules, and in the remaining part a different azide binding mode is observed. The 130 K EPR spectra of AO and laccase with azide (1:7) exhibit, in addition to an unperturbed T2 Cu(II) signal, new features in the g parallel region that are attributed to a perturbed T2 in protein molecules where the anti-ferromagnetic coupling of T3 has not been disrupted. While these features are also apparent in the AO : azide sample at 10 K, they are absent in the EPR spectra of the laccase : azide sample measured in the range of 6-90 K. Moreover, pulsed ENDOR measurements carried out at 4.2 K on the latter exhibited only a reduction in the intensity of the 20 MHz peak of the 14N histidine coordinated to the T2 Cu(II) but did not resolve any significant changes that could indicate azide binding to this ion. The lack of T2 Cu(II) signal perturbation below 90 K in laccase may be due to temperature dependence of the coupling within the trinuclear : azide complex.
自旋标记的低自旋高铁血红蛋白中的电子-电子自旋-自旋相互作用。
影响因子：
3.4
作者：
Budker,V;Du,JL;Seiter,M;Eaton,GR;Eaton,SS
通讯作者：
Eaton,SS
一氧化二氮还原酶中 [Cu(1.5) ... Cu(1.5)] 双核铜中心的电子自旋晶格弛豫。
影响因子：
3.4
作者：
Pfenninger,S;Antholine,WE;Barr,ME;Hyde,JS;Kroneck,PM;Zumft,WG
通讯作者：
Zumft,WG