Le Brun N E, Keech A M, Mauk M R, Mauk A G, Andrews S C, Thomson A J, Moore G R
Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, UK.
FEBS Lett. 1996 Nov 18;397(2-3):159-63. doi: 10.1016/s0014-5793(96)01172-6.
Divalent metal ion binding to the bacterial iron-storage protein, bacterioferritin (BFR), which contains a dinuclear metal binding site within each of its 24 subunits, was investigated by potentiometric and spectrophotometric methods. Cobalt(II) and zinc(II) were found to bind at both high- and low-affinity sites. Cobalt(II) binding at the high-affinity site was observed at a level of two per subunit with the release of approximately 1.6 protons per metal ion, thus confirming the dinuclear metal centre as the high-affinity site. Zinc(II) binding at the dinuclear centre (high-affinity site) resulted in the release of approximately 2 protons per metal ion, but exhibited a binding stoichiometry which indicated that not all dinuclear centres were capable of binding two zinc(II) ions. Competition data showed that binding affinities for the dinuclear centre were in the order zinc(II) > cobalt(II), and also confirmed the unexpected stoichiometry of zinc(II) binding. This work emphasises the importance of charge neutrality at the dinuclear centre.
通过电位滴定法和分光光度法研究了二价金属离子与细菌铁储存蛋白——细菌铁蛋白（BFR）的结合情况，该蛋白在其24个亚基中的每一个都含有一个双核金属结合位点。发现钴（II）和锌（II）在高亲和力和低亲和力位点均有结合。在高亲和力位点观察到每个亚基有两个钴（II）结合，每个金属离子释放约1.6个质子，从而证实双核金属中心为高亲和力位点。锌（II）在双核中心（高亲和力位点）结合导致每个金属离子释放约2个质子，但显示出的结合化学计量表明并非所有双核中心都能结合两个锌（II）离子。竞争数据表明，对双核中心的结合亲和力顺序为锌（II）>钴（II），也证实了锌（II）结合的意外化学计量。这项工作强调了双核中心电荷中性的重要性。
