| Autor: |
Stefan Franzen, Eric S. Peterson, Derek Brown, Steven G. Boxer, Joel M. Friedman, Melissa R. Thomas |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry. 269:4879-4886 |
| ISSN: |
0014-2956 |
| DOI: |
10.1046/j.1432-1033.2002.03193.x |
| Popis: |
Resonance Raman spectroscopy has been used to observe changes in the iron–ligand stretching frequency in photoproduct spectra of the proximal cavity mutant of myoglobin H93G. The measurements compare the deoxy ferrous state of the heme iron in H93G(L), where L is an exogenous imidazole ligand bound in the proximal cavity, to the photolyzed intermediate of H93G(L)*CO at 8 ns. There are significant differences in the frequencies of the iron–ligand axial out-of-plane mode ν(Fe–L) in the photoproduct spectra depending on the nature of L for a series of methyl-substituted imidazoles. Further comparison was made with the proximal cavity mutant of myoglobin in the absence of exogenous ligand (H93G) and the photoproduct of the carbonmonoxy adduct of H93G (H93G-*CO). For this case, it has been shown that H2O is the axial (fifth) ligand to the heme iron in the deoxy form of H93G. The photoproduct of H93G-*CO is consistent with a transiently bound ligand proposed to be a histidine. The data presented here further substantiate the conclusion that a conformationally driven ligand switch exists in photolyzed H93G-*CO. The results suggest that ligand conformational changes in response to dynamic motions of the globin on the nanosecond and longer time scales are a general feature of the H93G proximal cavity mutant. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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