The inter- and intra-electron and proton transfers in the nitrite reduction of copper-containing nitrite reductase (CuNiR) were investigated by using the QM/MM method with the calculational models containing type 1 (T1) and type 2 (T2) Cu sites. The electron transfer from the outer electron donor protein to the T1 Cu site occurred both before and after nitrite binding, and nitrite binding lowered the reduction potential of the Cu T1 site. The protonation of catalytic His244 subsequent to nitrite binding and T1 Cu reduction induced partial intra-electron transfer from T1 to T2 Cu sites. The proton transfer from His244 to nitrite bound on the T2 Cu site via the hydrogen bond network induced intra-electron transfer from the T1 to T2 Cu site. The interaction of the T1 Cu ligand with the second sphere amino acid residues and water molecules affected the reduction potential of the T1 Cu site. The water molecules in the so-called proton pool have an important role in the regulation of the basicity of His244. The conformation of the sensor loop did not change along the reaction, but the water molecule network extending along the sensor loop was changed by nitrite binding.

中文翻译：

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含铜亚硝酸盐还原酶中质子化诱导的电子内转移†

使用QM / MM方法，利用包含1型（T1）和2型（T2）铜位点的计算模型，研究了含铜亚硝酸还原酶（CuNiR）的亚硝酸还原中电子间和质子内部的转移。电子从外部电子供体蛋白到T1 Cu位的转移发生在亚硝酸盐结合之前和之后，而亚硝酸盐的结合降低了Cu T1位点的还原电位。亚硝酸盐结合和T1 Cu还原后催化His244的质子化导致部分电子内从T1转移到T2 Cu位。从His244的质子转移到亚硝酸盐在T2铜位点结合通过氢键网络诱导了电子从T1到T2 Cu位置的电子转移。T1 Cu配体与第二个球形氨基酸残基和水分子的相互作用影响了T1 Cu位点的还原电位。所谓的质子池中的水分子在His244碱度的调节中起着重要作用。传感器环的构象并未随反应而改变，但沿传感器环延伸的水分子网络却因亚硝酸盐的结合而发生了变化。