Sundararajan Mahesh, Hillier Ian H, Burton Neil A
School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom.
J Phys Chem B. 2007 May 17;111(19):5511-7. doi: 10.1021/jp066852o. Epub 2007 Apr 25.
The mechanism of nitrite reduction at the Cu(II) center of both copper nitrite reductase and a number of corresponding synthetic models has been investigated by using both QM/MM and cluster calculations employing density functional theory methods. The mechanism in both cases is found to be very similar. Initially nitrite is bound in a bidentate fashion to the Cu(II) center via the two oxygen atoms. Upon reduction of the copper center, the two possible coordination modes of the protonated nitrite, by either nitrogen or a single oxygen atom, are close in energy, with nitrogen coordination probably preferred. Further protonation of this species leads to N-O bond cleavage, and an electron transfer from the Cu(I) center to the N-O+ ligand, resulting in loss of NO and regeneration of the resting state of the enzyme having a bound water molecule.
利用密度泛函理论方法，通过量子力学/分子力学（QM/MM）和团簇计算，研究了亚硝酸铜还原酶以及一些相应合成模型中铜（II）中心处亚硝酸盐还原的机制。发现两种情况下的机制非常相似。最初，亚硝酸盐通过两个氧原子以双齿方式与铜（II）中心结合。铜中心还原后，质子化亚硝酸盐通过氮或单个氧原子的两种可能配位模式在能量上相近，可能更倾向于氮配位。该物种的进一步质子化导致N-O键断裂，以及一个电子从铜（I）中心转移到N-O⁺配体，导致NO损失并使具有结合水分子的酶的静止状态再生。
