Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Nadia 741252, India.
J Biol Inorg Chem. 2012 Apr;17(4):573-88. doi: 10.1007/s00775-012-0878-z. Epub 2012 Feb 17.
Isothermal calorimetric studies of the binding of iron(III) citrate to ferric ion binding protein from Neisseria gonorrhoeae suggested the complexation of a tetranuclear iron(III) cluster as a single step binding event (apparent binding constant K(app) (ITC) = 6.0(5) × 10(5) M(-1)). High-resolution Fourier transform ion cyclotron resonance mass spectrometric data supported the binding of a tetranuclear oxo(hydroxo) iron(III) cluster of formula Fe(4)O(2)(OH)(4)(H(2)O)(cit) in the interdomain binding cleft of FbpA. The mutant H9Y-nFbpA showed a twofold increase in the apparent binding constant [K(app) (ITC) = 1.1(7) × 10(6) M(-1)] for the tetranuclear iron(III) cluster compared to the wild-type protein. Mössbauer spectra of Escherichia coli cells overexpressing FbpA and cultured in the presence of added (57)Fe citrate were indicative of the presence of dinuclear and polynuclear clusters. FbpA therefore appears to have a strong affinity for iron clusters in iron-rich environments, a property which might endow the protein with new biological functions.
对来自淋病奈瑟菌的铁离子结合蛋白与柠檬酸铁(III)结合的等温热量法研究表明，四核铁(III)簇的络合是一个单步结合事件（表观结合常数 K(app)（ITC）= 6.0(5) × 10(5) M(-1)）。高分辨率傅里叶变换离子回旋共振质谱数据支持在 FbpA 的域间结合裂隙中结合四核氧（羟）铁(III)簇的化学式为Fe(4)O(2)(OH)(4)(H(2)O)(cit)。与野生型蛋白相比，突变体 H9Y-nFbpA 对四核铁(III)簇的表观结合常数 [K(app)（ITC）= 1.1(7) × 10(6) M(-1)] 增加了两倍。在添加了（57）Fe 柠檬酸的条件下过表达 FbpA 并培养的大肠杆菌细胞的穆斯堡尔谱表明存在双核和多核簇。因此，FbpA 似乎对富含铁的环境中的铁簇具有很强的亲和力，这种特性可能赋予该蛋白新的生物学功能。
