A (MU-OXO)BIS(MU-CARBOXYLATO)DIIRON(III) COMPLEX WITH A TETHERED PHENOXYL RADICAL AS A MODEL FOR THE ACTIVE-SITE OF THE R2 PROTEIN OF RIBONUCLEOTIDE REDUCTASE
A (MU-OXO)BIS(MU-CARBOXYLATO)DIIRON(III) COMPLEX WITH A TETHERED PHENOXYL RADICAL AS A MODEL FOR THE ACTIVE-SITE OF THE R2 PROTEIN OF RIBONUCLEOTIDE REDUCTASE
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DOI：
10.1021/ja00116a018
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发表时间：
1995-03-22
影响因子：
15
通讯作者：
LIPPARD, SJ
中科院分区：
文献类型：
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作者：
GOLDBERG, DP;KOULOUGLIOTIS, D;LIPPARD, SJ
我们设计并合成了一种新型双齿氮供体配体，1,1-双(2-(1-甲基咪唑基))-1-(3,5-二叔丁基-4-羟基苯基)乙烷(BIDPhEH) (2)。该配体的苯氧基自由基形式 BIDPhE (3) 被制备并分离为稳定的固体。 BIDPhEH 用于合成单核铁配合物 [Fe(BIDPhEH)(2)Cl-2]X (X = Cl (5a), FeCl4 (5b)。报告了 5b 的晶体学表征。使用溶剂配合物 [Fe2O(XDK)(MeOH)(5)(H2O)](NO3)(2)，其中 XDK 为间二甲苯二胺双(Kemp's 三酸)-酰亚胺是一种预组织的裂口形二羧酸配体，有助于制备苯氧基自由基(mu-oxo)-双(mu-羧基)二铁(III)络合物[Fe2O(XDK)(BIDPhE)(2)(NO3)(2)] (6)，这是一种包含R2蛋白活性位点的酪氨酰自由基的新模型大肠杆菌核糖核苷酸还原酶的磁化率研究表明，总体而言，铁原子的磁行为非常相似，并且数据的理论拟合确定 J 值 (H = -2JS(1).S-2) 为 -117 cm(-1)。与 R2 蛋白的饱和恢复 EPR 结果进行比较。
We have designed and synthesized a novel bidentate nitrogen donor ligand, 1,1-bis(2-(1-methylimidazolyl))-1-(3,5-di-tert-butyl-4-hydroxyphenyl)ethane (BIDPhEH) (2). The phenoxyl radical form of this ligand, BIDPhE (3), was prepared and isolated as a stable solid. BIDPhEH was used in the synthesis of the mononuclear ferric complex, [Fe(BIDPhEH)(2)Cl-2]X (X = Cl (5a), FeCl4 (5b). The crystallographic characterization of 5b is reported. Use of the solvento complex [Fe2O(XDK)(MeOH)(5)(H2O)](NO3)(2), where XDK is m-xylenediaminebis(Kemp's triacid)-imide, a pre-organized, cleft-shaped dicarboxylate ligand, facilitated preparation of the phenoxyl radical (mu-oxo)-bis(mu-carboxylato)diiron(III) complex [Fe2O(XDK)(BIDPhE)(2)(NO3)(2)] (6), a new model for the tyrosyl radical containing active site of the R2 protein of E. coli ribonucleotide reductase. Magnetic susceptibility studies of 6 revealed overall. magnetic behavior quite similar to that of the protein. The iron atoms are antiferromagnetically coupled, and a theoretical fit of the data determined the J value (H = -2JS(1).S-2) to be -117 cm(-1). Pulsed saturation-recovery EPR experiments conducted on 6 provided an independent measure of J, the value of which was in excellent agreement with the magnetic susceptibility measurements. Comparisons are made to the saturation-recovery EPR results for the R2 protein.