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Synthesis and characterization of IMPY derivatives that regulate metal-induced amyloid-β aggregation
Choi, Jung-Suk,Braymer, Joseph J.,Park, Se Kyung,Mustafa, Shaik,Chae, Junghyun,Lim, Mi Hee Royal Society of Chemistry 2011 Metallomics Vol.3 No.3
<P>Metal ions associated with amyloid-β (Aβ) species have been suggested to be involved in neurodegeneration leading to the progression of Alzheimer's disease (AD). The role of metal-involved Aβ species in AD neuropathogenesis, however, is not fully elucidated. In order to advance this understanding and contribute to the therapeutic development for AD, the rational structure-based design of small molecules that specifically target metal ions surrounded by Aβ species has recently received increased attention. To date, only a few compounds have been fashioned for this purpose. Herein, we report the design strategy, synthesis, characterization, and reactivity of new bifunctional IMPY derivatives K1 and K2. Using UV-vis and high-resolution two-dimensional (2D) NMR spectroscopy, the bifunctionality of K1 and K2 (metal chelation and Aβ interaction) was confirmed. These bifunctional IMPY derivatives showed preferential reactivity toward metal-induced Aβ aggregation over metal-free conditions in both <I>in vitro</I> inhibition and disaggregation experiments. Taken together, this study provides another example of a bifunctional small molecule framework that can target metal ions associated with Aβ species.</P> <P>Graphic Abstract</P><P>This study reports a framework of bifunctional small molecules that can target metal ions associated with Aβ species. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0mt00077a'> </P>
Structure and reactivity of a mononuclear non-haem iron(III)??peroxo complex
Cho, Jaeheung,Jeon, Sujin,Wilson, Samuel A.,Liu, Lei V.,Kang, Eun A.,Braymer, Joseph J.,Lim, Mi Hee,Hedman, Britt,Hodgson, Keith O.,Valentine, Joan Selverstone,Solomon, Edward I.,Nam, Wonwoo Nature Publishing Group, a division of Macmillan P 2011 Nature Vol.478 No.7370
Oxygen-containing mononuclear iron species??iron(iii)??peroxo, iron(iii)??hydroperoxo and iron(iv)??oxo??are key intermediates in the catalytic activation of dioxygen by iron-containing metalloenzymes. It has been difficult to generate synthetic analogues of these three active iron??oxygen species in identical host complexes, which is necessary to elucidate changes to the structure of the iron centre during catalysis and the factors that control their chemical reactivities with substrates. Here we report the high-resolution crystal structure of a mononuclear non-haem side-on iron(iii)??peroxo complex, [Fe(iii)(TMC)(OO)]<SUP>+</SUP>. We also report a series of chemical reactions in which this iron(iii)??peroxo complex is cleanly converted to the iron(iii)??hydroperoxo complex, [Fe(iii)(TMC)(OOH)]<SUP>2+</SUP>, via a short-lived intermediate on protonation. This iron(iii)??hydroperoxo complex then cleanly converts to the ferryl complex, [Fe(iv)(TMC)(O)]<SUP>2+</SUP>, via homolytic O??O bond cleavage of the iron(iii)??hydroperoxo species. All three of these iron species??the three most biologically relevant iron??oxygen intermediates??have been spectroscopically characterized; we note that they have been obtained using a simple macrocyclic ligand. We have performed relative reactivity studies on these three iron species which reveal that the iron(iii)??hydroperoxo complex is the most reactive of the three in the deformylation of aldehydes and that it has a similar reactivity to the iron(iv)??oxo complex in C??H bond activation of alkylaromatics. These reactivity results demonstrate that iron(iii)??hydroperoxo species are viable oxidants in both nucleophilic and electrophilic reactions by iron-containing enzymes.