Bacelo Daniel E, Binning R C
Department of Sciences and Technology, Universidad Metropolitana, P.O. Box 21150, San Juan, Puerto Rico.
J Phys Chem A. 2009 Feb 19;113(7):1189-98. doi: 10.1021/jp807170b.
Density functional theory optimizations have been conducted on structures of complexes of Fe(2+) with (H(2)O)(n) (n = 0-3) in three-residue models of binding sites A and B of the ferroxidase center of bullfrog M ferritin. Each site is modeled by the full structures of its three active amino acids. The potential surface at each site in the presence of water molecules is complex; coordination numbers of iron from three to six are seen. Water contributes to the complexity through its ability to hydrogen bond, to coordinate to iron, and to displace the neutral ligands glutamine and histidine. Intrinsic differences are noted at each site; at site B, the most stable complexes are found to favor tetracoordinate iron, while pentacoordination is preferred at site A in the two- and three-water complexes. While each incremental addition of a water molecule results in increased stability, successive binding energies are found to decrease.
在牛蛙M型铁蛋白铁氧化酶中心结合位点A和B的三残基模型中，对Fe(2+)与(H₂O)ₙ（n = 0 - 3）形成的配合物结构进行了密度泛函理论优化。每个位点由其三个活性氨基酸的完整结构建模。在存在水分子的情况下，每个位点的势能面都很复杂；观察到铁的配位数从3到6不等。水通过其氢键结合能力、与铁配位的能力以及取代中性配体谷氨酰胺和组氨酸的能力，增加了这种复杂性。每个位点都存在内在差异；在位点B，发现最稳定的配合物倾向于四配位铁，而在两个和三个水分子配合物中，位点A则优先形成五配位。虽然每次添加一个水分子都会导致稳定性增加，但发现连续的结合能会降低。
