Kuban R J, Wiesner R, Rathman J, Veldink G, Nolting H, Solé V A, Kühn H
Institute of Biochemistry, University Clinics Charité, Humboldt University, Hessische Str. 3-4, D-10115 Berlin, Germany.
Biochem J. 1998 May 15;332 ( Pt 1)(Pt 1):237-42. doi: 10.1042/bj3320237.
We investigated the geometry of the iron ligand sphere of the native rabbit 15-lipoxygenase (15-LOX) by X-ray absorption spectroscopy using synchrotron radiation. The soybean LOX-1 was used as a reference compound because its iron ligand sphere is well characterized. For structural information the X-ray absorption spectra were evaluated using the Excurve Program (CCLRC Daresbury Laboratory, Warrington, U.K.). From the positions of the absorption edges and from the intensities of the 1s-3d pre-edge transition peaks a six-coordinate ferrous iron was concluded for the rabbit 15-LOX. Evaluation of the extended region of the absorption spectra suggested six nitrogen and/or oxygen atoms as direct iron ligands, and the following binding distances were determined (means+/-S.D.; estimated accuracy is +/-0.001nm for bond distances, on the basis of more than 22 X-ray absorption spectra): 0.213+/-0.001nm, 0.213+/-0. 001 nm, 0.236+/-0.001 nm, 0.293+/-0.001 nm, 0.189+/-0.001 nm and 0. 242+/-0.001. Lyophilization of the LOX altered the binding distances but did not destroy the octahedral iron ligand sphere. For construction of a structural model of the iron ligand sphere the binding distances extracted from the X-ray spectra were assigned to specific amino acids (His-360, -365, -540, -544 and the C-terminal Ile-662) by molecular modelling using the crystal coordinates of the soybean LOX-1 and of a rabbit 15-LOX-inhibitor complex.
我们利用同步辐射X射线吸收光谱法研究了天然兔15-脂氧合酶（15-LOX）铁配体球的几何结构。大豆脂氧合酶-1（LOX-1）用作参考化合物，因为其铁配体球已得到充分表征。为获取结构信息，使用Excurve程序（英国沃灵顿CCLRC达累斯伯里实验室）对X射线吸收光谱进行评估。从吸收边的位置以及1s-3d预边跃迁峰的强度得出，兔15-LOX中的铁为六配位亚铁。对吸收光谱扩展区域的评估表明，有六个氮和/或氧原子作为铁的直接配体，并确定了以下结合距离（平均值±标准差；基于22多个X射线吸收光谱，键距的估计精度为±0.001nm）：0.213±0.001nm、0.213±0.001nm、0.236±0.001nm、0.293±0.001nm、0.189±0.001nm和0.242±0.001。脂氧合酶冻干改变了结合距离，但未破坏八面体铁配体球。为构建铁配体球的结构模型，利用大豆脂氧合酶-1和兔15-LOX-抑制剂复合物的晶体坐标，通过分子建模将从X射线光谱中提取的结合距离分配给特定氨基酸（His-360、-365、-540、-544和C端Ile-662）。
