Surface-enhanced resonance Raman scattering from cytochrome c and myoglobin adsorbed on a silver electrode

Abstract

16) The data in Table I show the fraction of the barrier that is eliminated after partial distortion of CBD from the rectangular minimum toward a square geometry. (17) Maier, G.; Schafer, U.; Sauer, W.; Hartan, H.; Oth, J. F. M. Tetrahedron Lett. 1978, 1837. This explanation has been suggested by Bally, T.;Masamune, S. Tetrahedron 1980,36,343. An alternative explanation is that C-1 and C-3, which are nonequivalent in a rectangular geometry, nevertheless, have nearly identical chemical shifts.(18) It should be noted that the geometry and apparent diamagnetic nature of 3 provide evidence for the correctness of the theoretical prediction of a singlet ground state for CBD, even at a square g e~m e t r y .~~~'~~~'~ (19) Buenker, R. J.; Peyerimhoff, S. D.

Resonance Raman spectra of heme c and heme d1 in Pseudomonas cytochrome oxidase

“…At present, it is not clear if the surface-erthanced spectra in [10] result from sample denaturation, selective enhancement of the low-spin component also present in their solution sample, or conformational changes due to the surface interactions. However, the observation in [19] that denaturation of ferric myoglobin may occur on an electrode surface, suggests that denaturation may be occurring in the Pseudomonas cytochrome oxidase case as well. Clearly, caution must be exercised in evaluating surface-enhanced Raman data from biological molecules.…”

Surface-Enhanced Raman Spectroscopy

“…This would allow the investigation of many biomolecular systems that denature on bare Ag or Au surfaces (86,87). Although metal colloids support surface plasmons and therefore should be viable SERS substrates, they still have many difficulties with regard to reproducibility and stability to changing environmental conditions.…”

Potential-dependent surface enhanced resonance Raman spectroscopy of cytochromec552 fromThermus thermophilus

“…4 In order to gain more insight into the mechanistic aspects of the redox reaction of we have Cyt-c 552 , employed surface-enhanced resonance Raman (SERR) spectroscopy to analyze the potential-dependent processes of this heme protein adsorbed on a silver electrode.5h7 The electrode/electrolyte interface is likely to exert electrostatic forces on the protein comparable to biological interfaces and, hence, may be regarded as an appropriate model system for charged binding domains of proteins also. 5,6,8,9 Moreover, SERR spectroscopy provides detailed structural information about the heme group exclusively of the adsorbed species so that it is a powerful technique for analyzing possible electrostatically induced changes of the active site structures which might be of functional relevance.6,9 Such investigations may provide valuable information about the coupling between electron-transfer reactions and conformational transitions and may contribute to the elucidation of the molecular mechanism of the biological redox process.…”