Bell S H, Weir M P, Dickson D P, Gibson J F, Sharp G A, Peters T J
Biochim Biophys Acta. 1984 Jun 28;787(3):227-36. doi: 10.1016/0167-4838(84)90313-3.
Ferritin and haemosiderin isolated from iron-overloaded human spleens have been investigated by 57Fe Mössbauer spectroscopy at temperatures between 1.3 and 200 K and also in applied magnetic fields. Virtually identical spectra were obtained from both materials at the high and low-temperature ends of this range, and also at 4.2 K in an applied magnetic field of 10 T; this indicates that both must contain iron in a closely similar chemical form. The difference between the two materials lies in the temperature dependence of their Mössbauer spectra in the intermediate temperature range, between 10 and 100 K. The temperature dependence of the Mössbauer spectra is characteristic of superparamagnetic behaviour, which occurs when a magnetically ordered material is present in the form of small particles. The details of this temperature dependence are related to the distribution of particle sizes and the magnetic anisotropy constant of each substance. Electron microscopy shows the haemosiderin cores to be markedly smaller on average than those of ferritin. Combining the Mössbauer spectroscopy and electron microscopy data we have shown that the magnetic anistropy constant of haemosiderin is considerably larger than that of ferritin. This is thought to result from the smaller core size and less symmetrical protein shell of the former. These data are consistent with the proposal that haemosiderin is derived from ferritin.
通过57Fe穆斯堡尔谱在1.3至200 K的温度范围内以及在施加磁场的情况下，对从铁过载的人脾脏中分离出的铁蛋白和含铁血黄素进行了研究。在该温度范围的高温和低温端，以及在10 T的外加磁场中的4.2 K下，从这两种物质中获得了几乎相同的光谱；这表明两者必定都含有化学形式极为相似的铁。这两种物质之间的差异在于它们的穆斯堡尔谱在10至100 K的中间温度范围内对温度的依赖性。穆斯堡尔谱对温度的依赖性是超顺磁行为的特征，当磁性有序材料以小颗粒形式存在时就会出现这种行为。这种温度依赖性的细节与颗粒尺寸的分布以及每种物质的磁各向异性常数有关。电子显微镜显示，含铁血黄素核心的平均尺寸明显小于铁蛋白的核心。结合穆斯堡尔谱和电子显微镜数据，我们已经表明含铁血黄素的磁各向异性常数远大于铁蛋白的磁各向异性常数。据认为，这是由于前者的核心尺寸较小且蛋白质外壳的对称性较低所致。这些数据与含铁血黄素源自铁蛋白的提议一致。
