Department of Inorganic and Analytical Chemistry, University of Debrecen, 4032, Debrecen, Hungary.
Research Centre for Natural Sciences, 1117, Budapest, Hungary.
Chemistry. 2020 Dec 15;26(70):16767-16773. doi: 10.1002/chem.202002706. Epub 2020 Nov 9.
Detailed equilibrium, spectroscopic and superoxide dismutase (SOD) activity studies are reported on a nickel complex formed with a new metallopeptide bearing two nickel binding loops of NiSOD. The metallopeptide exhibits unique nickel binding ability and the binuclear complex is a major species with 2×(NH ,N ,S ,S ) donor set even in an equimolar solution of the metal ion and the ligand. Nickel(III) species were generated by oxidizing the Ni complexes with KO and the coordination modes were identified by EPR spectroscopy. The binuclear complex formed with the binding motifs exhibits superior SOD activity, in this respect it is an excellent model of the native NiSOD enzyme. A detailed kinetic model is postulated that incorporates spontaneous decomposition of the superoxide ion, the dismutation cycle and fast redox degradation of the binuclear complex. The latter process leads to the elimination of the SOD activity. A unique feature of this system is that the Ni form of the catalyst rapidly accumulates in the dismutation cycle and simultaneously the Ni form becomes a minor species.
详细的平衡、光谱和超氧化物歧化酶（SOD）活性研究报告了一种镍配合物的形成，该配合物带有两个镍结合环的 NiSOD 新金属肽。该金属肽具有独特的镍结合能力，双核配合物是主要物种，即使在金属离子和配体的等摩尔溶液中，也具有 2×（NH ，N ，S ，S ）供体集。用 KO 氧化 Ni 配合物可生成镍（III）物种，通过 EPR 光谱鉴定了配位模式。与结合基序形成的双核配合物表现出优异的 SOD 活性，在这方面，它是天然 NiSOD 酶的理想模型。提出了一个详细的动力学模型，该模型包含了超氧离子的自发分解、歧化循环和双核配合物的快速氧化还原降解。后一过程导致 SOD 活性的消除。该系统的一个独特特征是催化剂的 Ni 形式在歧化循环中迅速积累，同时 Ni 形式成为次要物质。
