Attia Amr A A, Silaghi-Dumitrescu Radu
Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Cluj-Napoca, Romania.
J Mol Graph Model. 2016 Sep;69:103-10. doi: 10.1016/j.jmgm.2016.09.001. Epub 2016 Sep 2.
The ability of mononuclear non-heme iron complexes to function as molecular oxygen transporters is investigated by density functional theory. The factors governing the efficiency of the reversible binding of dioxygen at the active site of the dinuclear non-heme iron enzyme hemerythrin, including antiferromagnetic coupling and the conversion of dioxygen to hydroperoxo by a proton coupled 2-electron transfer mechanism, are revisited and considered as possible tools in mononuclear non-heme complexes. Several mononuclear non-heme model complexes, including active sites of enzymes already known to interact with dioxgenic ligands, are constructed and the molecular oxygen transportation capabilities of these complexes are examined computationally. The high-spin nature of the ground state of these complexes implies an intrinsic kinetic lability of the oxy structures, as also evident from potential energy surface calculations towards iron-dioxygen cleavage. Proton affinities as calibrated with reference compounds showed that these complexes are highly unlikely to undergo protonation to form hydroperoxo-like adducts. Mixed superoxo descriptions of the dissociated dioxygenic ligands in all complexes add to the overall conclusion that these model structures are significantly disadvantaged in any attempt to be employed for molecular oxygen transportation.
通过密度泛函理论研究单核非血红素铁配合物作为分子氧转运体的能力。重新审视了控制双核非血红素铁酶血蓝蛋白活性位点上双氧可逆结合效率的因素，包括反铁磁耦合以及通过质子耦合双电子转移机制将双氧转化为氢过氧根，并将其视为单核非血红素配合物中可能的工具。构建了几种单核非血红素模型配合物，包括已知与双氧配体相互作用的酶的活性位点，并通过计算研究了这些配合物的分子氧运输能力。这些配合物基态的高自旋性质意味着氧结构具有内在的动力学不稳定性，这也从铁-氧裂解的势能面计算中明显看出。用参考化合物校准的质子亲和力表明，这些配合物极不可能发生质子化形成类似氢过氧根的加合物。所有配合物中解离的双氧配体的混合超氧描述进一步支持了总体结论，即这些模型结构在用于分子氧运输的任何尝试中都存在显著劣势。
