80528-41-2Relevant articles and documents
SYNTHESIS AND PROPERTIES OF BINUCLEAR COBALT(II) OXYGEN ADDUCT WITH 2,6-BIS-4-METHYLPHENOL
Suzuki, Masatatsu,Kanatomi, Hajime,Murase, Ichiro
, p. 1745 - 1748 (1981)
Binuclear cobalt(II) complexes, ClO4 and (ClO4)2 with 2,6-bis-4-methylphenol (Hbpmp), were prepared.The complexes showed the reversible oxygenation in various solvents.Two to one (Co/
The Semireduced Mechanism for Nitric Oxide Reduction by Non-Heme Diiron Complexes: Modeling Flavodiiron Nitric Oxide Reductases
White, Corey J.,Speelman, Amy L.,Kupper, Claudia,Demeshko, Serhiy,Meyer, Franc,Shanahan, James P.,Alp, E. Ercan,Hu, Michael,Zhao, Jiyong,Lehnert, Nicolai
, p. 2562 - 2574 (2018/02/28)
Flavodiiron nitric oxide reductases (FNORs) are a subclass of flavodiiron proteins (FDPs) capable of preferential binding and subsequent reduction of NO to N2O. FNORs are found in certain pathogenic bacteria, equipping them with resistance to nitrosative stress, generated as a part of the immune defense in humans, and allowing them to proliferate. Here, we report the spectroscopic characterization and detailed reactivity studies of the diiron dinitrosyl model complex [Fe2(BPMP)(OPr)(NO)2](OTf)2 for the FNOR active site that is capable of reducing NO to N2O [Zheng et al., J. Am. Chem. Soc. 2013, 135, 4902-4905]. Using UV-vis spectroscopy, cyclic voltammetry, and spectro-electrochemistry, we show that one reductive equivalent is in fact sufficient for the quantitative generation of N2O, following a semireduced reaction mechanism. This reaction is very efficient and produces N2O with a first-order rate constant k > 102 s-1. Further isotope labeling studies confirm an intramolecular N-N coupling mechanism, consistent with the rapid time scale of the reduction and a very low barrier for N-N bond formation. Accordingly, the reaction proceeds at -80 °C, allowing for the direct observation of the mixed-valent product of the reaction. At higher temperatures, the initial reaction product is unstable and decays, ultimately generating the diferrous complex [Fe2(BPMP)(OPr)2](OTf) and an unidentified ferric product. These results combined offer deep insight into the mechanism of NO reduction by the relevant model complex [Fe2(BPMP)(OPr)(NO)2]2+ and provide direct evidence that the semireduced mechanism would constitute a highly efficient pathway to accomplish NO reduction to N2O in FNORs and in synthetic catalysts.
Design of coordination interaction of Zn(II) complex with oligo-aspartate peptide to afford a high-affinity tag-probe pair
Fuchida, Hirokazu,Tabata, Shigekazu,Shindo, Naoya,Takashima, Ippei,Leng, Qiao,Hatsuyama, Yuji,Hamachi, Itaru,Ojida, Akio
supporting information, p. 784 - 791 (2015/06/25)
A complementary recognition pair consisting of a genetically encodable peptide tag and a small molecular probe isa powerful tool to specifically label and manipulate a protein ofinterest under biological conditions. In this study, we report the redesign of a tag-probe pair comprising an oligo-aspartate peptide tag (such as DDDD) and a binuclear zinc complex. Isothermal-titration calorimetry screening of binding between the series of peptides and zinc complexes revealed that the binding affinity was largely influenced by subtle changes of the ligand structure of the probe. However, the binding was tolerant to differences of the tag peptide sequence. Of those tested, a pair containing a peptide tag (DDAADD) and a binuclear zinc complex possessing 4-chloropyridines (3-2Zn(II)) showed the strongest binding affinity (Ka = 3.88 × 105 M-1), which was about 10-fold larger than the conventional pair of D4-peptide tag (DDDD) and 1-2Zn(II) containing nonsubstituted pyridines (Ka = 3.73 × 104 M-1). The strong binding of this new complementary recognition pair enabled the rapid covalent labeling of a tag-fused maltose binding protein with a fluorescent zinc complex, demonstrating its potential utility in protein analysis.