Probing the Ternary Complexes of Indoleamine and Tryptophan 2,3-Dioxygenases by Cryoreduction EPR and ENDOR Spectroscopy
| Autor: | J. L. Ross Anderson, Stephen K Chapman, Sarah J. Thackray, Emma Lloyd Raven, Christopher G. Mowat, Roman Davydov, Nishma Chauhan, Brian M. Hoffman, Nektaria D. Papadopoulou |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
inorganic chemicals
Chemistry(all) Double bond Protonation 010402 general chemistry Photochemistry Xanthomonas campestris 01 natural sciences Biochemistry Catalysis Article 03 medical and health sciences Colloid and Surface Chemistry Dioxygenase Catalytic Domain Humans Indoleamine-Pyrrole 2 3 -Dioxygenase Ferrous Compounds 030304 developmental biology Indole test chemistry.chemical_classification 0303 health sciences Substrate Interaction Ligand Hydrogen bond Chemistry Electron Spin Resonance Spectroscopy Tryptophan Substrate (chemistry) Hydrogen Bonding General Chemistry Tryptophan Oxygenase 0104 chemical sciences Oxygen Crystallography |
| Zdroj: | Journal of the American Chemical Society Davydov, R M, Chauhan, N, Thackray, S J, Anderson, J L R, Papadopoulou, N D, Mowat, C G, Chapman, S K, Raven, E L & Hoffman, B M 2010, ' Probing the Ternary Complexes of Indoleamine and Tryptophan 2,3-Dioxygenases by Cryoreduction EPR and ENDOR Spectroscopy ', Journal of the American Chemical Society, vol. 132, no. 15, pp. 5494-5500 . https://doi.org/10.1021/ja100518z |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja100518z |
| Popis: | We have applied cryoreduction/EPR/ENDOR techniques to characterize the active-site structure of the ferrous-oxy complexes of human (hIDO) and Shewanella oneidensis (sIDO) indoleamine 2,3-dioxygenases, Xanthomonas campestris (XcTDO) tryptophan 2,3-dioxygenase, and the H55S variant of XcTDO in the absence and in the presence of the substrate L-Trp and a substrate analogue, L-Me-Trp. The results reveal the presence of multiple conformations of the binary ferrous-oxy species of the IDOs. In more populated conformers, most likely a water molecule is within hydrogen-bonding distance of the bound ligand, which favors protonation of a cryogenerated ferric peroxy species at 77 K. In contrast to the binary complexes, cryoreduction of all of the studied ternary [enzyme-O-2-Trp] dioxygenase complexes generates a ferric peroxy heme species with very similar EPA and H-1 ENDOR spectra in which protonation of the basic peroxy ligand does not occur at 77 K. Parallel studies with L-Me-Trp, in which the proton of the indole nitrogen is replaced with a methyl group, eliminate the possibility that the indole NH group of the substrate acts as a hydrogen bond donor to the bound O-2, and we suggest instead that the ammonium group of the substrate hydrogen-bonds to the dioxygen ligand. The present data show that substrate binding, primarily through this H-bond, causes the bound dioxygen to adopt a new conformation, which presumably is oriented for insertion of O-2 into the C-2-C-3 double bond of the substrate. This substrate interaction further helps control the reactivity of the heme-bound dioxygen by "shielding" it from water. |
| Databáze: | OpenAIRE |
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