The trinuclear copper center (TNC) of laccase reduces oxygen to water with very little overpotential. The arrangement of the coppers and ligands in the TNC is known to be from many crystal structures, yet information about possible dynamics of the ligands is absent. Here, we report dynamics at the TNC of small laccase from Streptomyces coelicolor using paramagnetic NMR and electron paramagnetic resonance spectroscopy. Fermi contact-shifted resonances tentatively assigned to histidine Hδ1 display a two-state chemical exchange with exchange rates in the order of 100 s−1. In the electron paramagnetic resonance spectra, at least two forms are observed with different gz-values. It is proposed that the exchange processes reflect the rotational motion of histidine imidazole rings that coordinate the coppers in the TNC.

中文翻译：

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天蓝色链霉菌小漆酶三核铜中心的化学交换。

漆酶的三核铜中心 (TNC) 将氧还原为水，而超电势很小。已知 TNC 中铜和配体的排列来自许多晶体结构，但缺乏有关配体可能动力学的信息。在这里，我们使用顺磁 NMR 和电子顺磁共振波谱报告了来自天蓝色链霉菌的小漆酶在 TNC 的动力学。暂时分配给组氨酸 Hδ1 的费米接触位移共振显示出一种二态化学交换，交换率约为 100 s-1。在电子顺磁共振谱中，至少观察到两种具有不同 gz 值的形式。提出交换过程反映了协调 TNC 中铜的组氨酸咪唑环的旋转运动。