Miller M A, Shaw A, Kraut J
Department of Chemistry, University of California, San Diego La Jolla 92093-0317.
Nat Struct Biol. 1994 Aug;1(8):524-31. doi: 10.1038/nsb0894-524.
The Fe+3-OOH complex of peroxidases has a very short half life, and its structure cannot be determined by conventional methods. The Fe+2-O2 complex provides a useful structural model for this intermediate, as it differs by only one electron and one proton from the transient Fe+3-OOH complex. We therefore determined the crystal structure of the Fe+2-O2 complex formed by a yeast cytochrome c peroxidase mutant with Trp 191 replaced by Phe. The refined structure shows that dioxygen can form a hydrogen bond with the conserved distal His residue, but not with the conserved distal Arg residue. When the transient Fe+3-OOH complex is modelled in a similar orientation, the active site of peroxidase appears to be optimized for catalysing proton transfer between the vicinal oxygen atoms of the peroxy-anion.
过氧化物酶的Fe+3-OOH复合物半衰期非常短，其结构无法用传统方法确定。Fe+2-O2复合物为该中间体提供了一个有用的结构模型，因为它与瞬态Fe+3-OOH复合物仅相差一个电子和一个质子。因此，我们确定了酵母细胞色素c过氧化物酶突变体（其中Trp 191被Phe取代）形成的Fe+2-O2复合物的晶体结构。优化后的结构表明，双氧可与保守的远端His残基形成氢键，但不能与保守的远端Arg残基形成氢键。当以相似方向模拟瞬态Fe+3-OOH复合物时，过氧化物酶的活性位点似乎经过优化，可催化过氧阴离子邻位氧原子之间的质子转移。
