ISSN:
0377-0486
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Visible excitation resonance Raman difference spectra, in resonance with the 605-nm absorption maximum of fully reduced and mixed-valence cyanide-bound cytochrome oxidase, were recorded. Under these conditions, the vibrations of ferrocytochrome a are markedly enhanced owing to its dominant contribution to the 605-nm α-band absorption of reduced cytochrome oxidase. The effect of H/D exchange in the Raman spectra of cytochrome a was also investigated as a way to establish formyl- and vinyl-peripheral substituent sensitive modes. Measurements of the depolarization ratio dependence of cytochrome a vibrational modes resulted in some isotope-sensitive modes with characteristic depolarized behavior; however, it was observed that the majority of the visible excitation vibrations exhibit polarized values. This is interpreted as being due to a significant lowering in the molecular symmetry of the heme a porphyrin macrocycle caused by the unusual peripheral substituent pattern of heme a and, presumably, by the strong cytochrome a-protein interactions. Both structural effects appear to result in a selective enhancement of cytochrome a Eu substituent-sensitive modes as detected by the low-frequency resonance Raman spectrum.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jrs.1250220212
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