The sulfonium ion linkage in myeloperoxidase. Direct spectroscopic detection by isotopic labeling and effect of mutation
| Autor: | I M, Kooter, N, Moguilevsky, A, Bollen, L A, van der Veen, C, Otto, H L, Dekker, R, Wever |
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| Rok vydání: | 1999 |
| Předmět: |
Electron Spin Resonance Spectroscopy
Sulfonium Compounds CHO Cells Heme Hydrogen-Ion Concentration Spectrum Analysis Raman Transfection Hydrocarbons Amino Acid Substitution Chlorides Models Chemical Cricetinae Spectroscopy Fourier Transform Infrared Mutagenesis Site-Directed Animals Methane Oxidation-Reduction Peroxidase |
| Zdroj: | The Journal of biological chemistry. 274(38) |
| ISSN: | 0021-9258 |
| Popis: | The heme group of myeloperoxidase is covalently linked via two ester bonds to the protein and a unique sulfonium ion linkage involving Met(243). Mutation of Met(243) into Thr, Gln, and Val, which are the corresponding residues of eosinophil peroxidase, lactoperoxidase, and thyroid peroxidase, respectively, and into Cys was performed. The Soret band in the optical absorbance spectrum in the oxidized mutants is now found at approximately 411 nm. Both the pyridine hemochrome spectra and resonance Raman spectra of the mutants are affected by the mutation. In the Met(243) mutants the affinity for chloride has decreased 100-fold. All mutants have lost their chlorination activity, except for the M243T mutant, which still has 15% activity left. By Fourier transform infared difference spectroscopy it was possible to specifically detect the (13)CD(3)-labeled methionyl sulfonium ion linkage. We conclude that the sulfonium ion linkage serves two roles. First, it serves as an electron-withdrawing substituent via its positive charge, and, second, together with its neighboring residue Glu(242), it appears to be responsible for the lower symmetry of the heme group and distortion from the planar conformation normally seen in heme-containing proteins. |
| Databáze: | OpenAIRE |
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