Characterization of the Fe(III)-binding site in Sepia eumelanin by resonance Raman confocal microspectroscopy

Alexander Samokhvalov, Yan Liu, John D. Simon

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Abstract

The resonance Raman spectrum of Sepia eumelanin is discussed by analogy to model compounds containing catechol (CAT)-like structural units. These data are then compared with the analogous data on Fe(III)-enriched Sepia eumelanin. In contrast to the natural eumelanin, the Fe(III)-enriched samples exhibit absorption features in the visible and near-IR spectral regions, which are attributed to ligand-to-metal charge-transfer (LMCT) bands. Resonance Raman spectra collected by exciting these LMCT bands reveal bands at 580 and 1470 cm-1; the intensity of these features increases with increasing Fe(III) content. The 580 and 1470 cm-1 bands are assigned to Fe-OR stretching and ring deformation modes, respectively. These data further substantiate that the Fe(III)-melanin-binding site in melanin is composed of CAT-like structural units.

Original languageEnglish
Pages (from-to)84-88
Number of pages5
JournalPhotochemistry and Photobiology
Volume80
Issue number1
DOIs
Publication statusPublished - Jul 1 2004

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ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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