53716-58-8Relevant articles and documents
Solid-state deuterium nmr of imidazole ligands in cytochrome C peroxidase
Liu, Kai,Williams, John,Lee, Hyerim,Fitzgerald, Melissa M.,Jensen, Gerard M.,Goodin, David B.,McDermott, Ann E.
, p. 10199 - 10202 (1998)
We have measured hyperfine shifted NMR signals associated with deuterated imidazole bound to the high-spin Fe3+ state of cytochrome c peroxidase using deuterium magic angle spinning solid-state NMR. These experiments were performed on a mutant of cytochrome c peroxidase, CcP(H175G), for which replacement of the proximal histidine with glycine produced a cavity that can bind a variety of substituted imidazoles including imidazole or 2-methylimidazole. The mutant with imidazole bound is inactive; specifically its reaction with H2O2 is blocked. We observed deuterium NMR signals from the methyl-d3 group of the perdeuterated 2-MeIm sample bound to H175G CcP. The signal displayed an upfield chemical shift and exhibited non- Curie temperature dependence, indicating the existence of low-lying excited electronic states. Upon introducing a nondeuterated competitive ligand, imidazole, a decrease in the intensity of this signal was detected, consistent with the assignment of the deuterium signal to the bound 2- methylimidazole in the solid state. The tensor of the deuterium static line shape indicates the methyl group on the untethered imidazole ring undergoes rather unhindered motion while the entire ring has relatively limited motion. No evidence for intermediate ring flipping exchange dynamics nor for large angular librations of the ring is observed. This the absence of enzymatic activity in the mutant is unlikely to result from excessive dynamic disorder of the untethered imidazole.
Resonance Raman Spectra of Dioxygen Adducts of Cobalt Porphyrin-Imidazole Complexes. Remarkable Spectroscopic Consequences of Hydrogen Bonding of the Coordinated Imidazole and the Lack of an Effect on the Cobalt-Oxygen Linkage
Proniewicz, Leonard M.,Bruha, Alan,Nakamoto, Kazuo,Kyuno, Eishin,Kincaid, James R.
, p. 7050 - 7056 (1989)
Resonance Raman (RR) spectroscopic studies of O2 adducts of the imidazole complexes of a highly protected cobalt-porphyrin are reported.Strategic isotopic labeling studies, employing dioxygen isotopomers and selectively deuteriated imidazole analogues, are used to document and interpret the complicated spectral patterns that emerge as a result of complex vibrational coupling of ν(O-O) with internal modes of the trans-coordinated imidazole ligand.In addition, the observed spectral patterns are shown to be dependent upon temperature, imidazole concentration, and theaddition of a hydrogen-bond acceptor.These results indicate that hydrogen bonding of the ligated imidazole to other solution components does not lead to differences in the inherent frequency of ν(O-O) but does result in dramatic alterations of the observed spectral patterns as a consequence of diferences in vibrational coupling parameters.The implications of these studies for the interpretation of RR spectra of O2 adducts of cobalt-substituted hemeproteins are discused.
Vibrational analysis of the imidazolate ring
Hashimoto, Shinji,Ono, Kunio,Takeuchi, Hideo,Harada, Issei
, p. 1647 - 1660 (2007/10/02)
IR and Raman spectra have been investigated for imidazolate and 4-methylimidazolate including five and three deuterated analogs, respectively.Assignment of the observed IR and Raman bands has been made on the basis of isotopic frequency shifts, Raman polarization properties, and normal coordinate calculations.The calculated normal frequencies are in good agreement with experimental ones: the average error below 1600 cm-1 is 4.5 cm-1 for 104 in-plane vibrations and 3.8 cm-1 for 43 out-of-plane vibrations.The calculated vibrational modes are useful in analyzing thc Raman bands of histidine residues in proteins.
