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Effects of thioether substituents on the O2 reactivity of beta-diketiminate-Cu(I) complexes: probing the role of the methionine ligand in copper monooxygenases.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Aboelella, Nermeen W. Gherman, Benjamin F. Hill, Lyndal M. R. Holm, Nicole Young, Victor G. Cramer, Christopher J. Tolman, William B. |
| Copyright Year | 2006 |
| Abstract | The activation of dioxygen by dopamine beta-monooxygenase (DbetaM) and peptidylglycine alpha-hydroxylating monooxygenase (PHM) is postulated to occur at a copper site ligated by two histidine imidazoles and a methionine thioether, which is unusual because such thioether ligation is not present in other O2-activating copper proteins. To assess the possible role of the thioether ligand in O2 activation by DbetaM and PHM, two new ligands comprising beta-diketiminates with thioether substituents were synthesized and Cu(I) and Cu(II) complexes were isolated. The Cu(II) compounds are monomeric and exhibit intramolecular thioether coordination. While the Cu(I) complexes exhibit a multinuclear topology in the solid state, variable-temperature 1H NMR studies implicate equilibria in solution, possibly including monomers with intramolecular thioether coordination that are structurally defined by DFT calculations. Low-temperature oxygenation of solutions of the Cu(I) complexes generates stable 1:1 Cu/O2 adducts, which on the basis of combined experimental and theoretical studies adopt side-on "eta(2)" structures with negligible Cu-thioether bonding and significant peroxo-Cu(III) character. In contrast to previously reported findings with related ligands lacking the thioether group, however (cf., Aboelella; et al. J. Am. Chem. Soc. 2004, 126, 16896), purging the solutions of the thioether-containing adducts with argon results in conversion to bis(mu-oxo)dicopper(III) species. A role for the thioether in promoting loss of O2 from the 1:1 Cu/O2 adduct and facilitating trapping of the resulting Cu(I) complex to yield the bis(mu-oxo) species is proposed, and the possible relevance of this role to that of the methionine in the active sites of DbetaM and PHM is discussed. |
| Starting Page | 9 |
| Ending Page | 17 |
| Page Count | 9 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.csus.edu/indiv/g/ghermanb/publications/ja057745vsi20051114_030249.pdf |
| Alternate Webpage(s) | http://www.csus.edu/indiv/g/ghermanb/publications/ja057745v.pdf |
| PubMed reference number | 16522125v1 |
| Volume Number | 128 |
| Issue Number | 10 |
| Journal | Journal of the American Chemical Society |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Anatomy, Regional Argon Cell Respiration Chorionic Gonadotropin, beta Subunit, Human Copper Cuprous Dioxygen Dopamine Histidine Imidazoles Ligands Ligation Methionine Mixed Function Oxygenases Ornithine-oxo-acid aminotransferase Oxygen Promotion (action) Pyschological Bonding Sensorineural Hearing Loss (disorder) Solutions Thioethers adduct alpha-Mannosidosis bis(mu-propionato)diaquatetrabromodirhenium (III) cupric cation monomer potassium oxonate |
| Content Type | Text |
| Resource Type | Article |
