RECONSTITUTED AND NATIVE IRON-CORES OF BACTERIOFERRITIN AND FERRITIN
RECONSTITUTED AND NATIVE IRON-CORES OF BACTERIOFERRITIN AND FERRITIN
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DOI：
10.1016/0022-2836(87)90290-7
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发表时间：
1987-12-05
影响因子：
5.6
通讯作者：
HARRISON, PM
中科院分区：
文献类型：
--
作者：
MANN, S;WILLIAMS, JM;HARRISON, PM
用高分辨透射电镜、电子衍射和穆斯堡尔谱研究了重组马脾铁蛋白和棕色固氮菌铁蛋白的铁核结构和磁性。天然马脾铁蛋白，天然AZ。vinelandii和天然的和重建的铜绿假单胞菌菌铁蛋白也已确定。在不存在无机磷酸盐的情况下在pH 7.0下的重构在每种蛋白质中显示S形行为，但对于Az，初始速率快约30%。vinelandii蛋白与马脾脱铁蛋白相比。Zn ~（2+）的存在降低了Fe（II）在AZ中的氧化初始速率。vinelandii的防效为22%。重组细菌铁蛋白的铁核心采用缺陷的水铁矿结构，并且比它们的天然对应物更高度有序，这两者都是无定形的。然而，对于重构的Az. vinelandii（22.2 K）与天然蛋白（20 K）几乎相同。粒度测量表明，重构的Az. vinelandii核的中值直径小于天然核，并且颗粒体积（V）的这种减小抵消了磁晶对磁各向异性常数（K）的增加的贡献，使得磁各向异性势垒（KV）以及因此的阻断温度对于两种蛋白质是相似的。重建马脾铁蛋白表现出类似的阻断温度（38 K），确定为天然蛋白质，虽然它是结构上更无序。通过体外重构在马铁蛋白和细菌铁蛋白中引入结构和组成修饰的可能性表明，这些蛋白质不主要作为体内核心开发的晶体化学特异性界面起作用。
The structural and magnetic properties of the iron-cores of reconstituted horse spleen ferritin and Azotobacter vinelandii bacterioferritin have been investigated by high-resolution transmission electron microscopy, electron diffraction and Mossbauer spectroscopy. The structural properties of native horse spleen ferritin, native Az. vinelandii, and native and reconstituted Pseudomonas aeruginosa bacterioferritins have also been determined. Reconstitution in the absence of inorganic phosphate at pH 7.0 showed sigmoidal behaviour in each protein but was approximately 30% faster in initial rate for the Az. vinelandii protein when compared with horse spleen apoferritin. The presence of Zn2+ reduced the initial rate of Fe(II) oxidation in Az. vinelandii to 22% of the control rate. The iron-cores of the reconstituted bacterioferritins adopt defect ferrihydrite structures and are more highly ordered than their native counterparts, which are both amorphous. However, the blocking temperature for reconstituted Az. vinelandii (22.2 K) is almost identical to that for the native protein (20 K). Particle size measurements indicate that the reconstituted Az. vinelandii cores are smaller in median diameter than the native cores and this reduction in particle volume (V) offsets the increased magnetocrystalline contribution to the magnetic anisotropy constant (K) in such a way that the magnetic anisotropy barrier (KV), and hence the blocking temperature, is similar for both proteins. Reconstituted horse spleen ferritin exhibits a similar blocking temperature (38 K) to that determined for the native protein, although it is structurally more disordered. The possibility of introducing structural and compositional modifications in both horse ferritin and bacterioferritins by in-vitro reconstitution suggests that these proteins do not function primarly as a crystallochemical-specific interface for core development in vivo.