Blackburn N J, Hasnain S S, Binsted N, Diakun G P, Garner C D, Knowles P F
Biochem J. 1984 May 1;219(3):985-90. doi: 10.1042/bj2190985.
Copper and zinc K-edge e.x.a.f.s. (extended X-ray-absorption fine structures) were measured for the metal sites of oxidized and reduced bovine superoxide dismutase in aqueous solution. Detailed analysis of the spectra indicates that the copper site of the enzyme changes on reduction and is most probably co-ordinated to three imidazole groups at a shorter distance Cu-N(alpha) = 0.194 nm (1.94 A) in the reduced form compared with a co-ordination of four imidazole groups at 0.199 nm (1.99 A) and an oxygen atom from solvent water at 0.224 nm (2.24 A) in the oxidized form. Examination of the edge, near-edge structure and e.x.a.f.s. of the zinc sites indicates that the stereochemical changes at copper that accompany reduction introduce minimal perturbation on the stereochemistry at zinc.
对水溶液中氧化态和还原态牛超氧化物歧化酶的金属位点进行了铜和锌K边扩展X射线吸收精细结构(EXAFS)测量。光谱的详细分析表明,酶的铜位点在还原时发生变化,还原态时最有可能与三个咪唑基团配位,Cu-N(α) = 0.194 nm(1.94 Å),相比之下,氧化态时与四个咪唑基团配位,距离为0.199 nm(1.99 Å),并与溶剂水分子中的一个氧原子配位,距离为0.224 nm(2.24 Å)。对锌位点的边缘、近边缘结构和EXAFS的研究表明,还原时铜位点的立体化学变化对锌位点的立体化学产生的扰动最小。