title: Characterization of the Fe(III)-binding site in Sepia eumelanin by resonance Raman confocal microspectroscopy.
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.
authors.affiliation: Department of Chemistry, Duke University, Durham, NC 27708-0346, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Samokhvalov
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: John D
authors.initials: JD
authors.lastname: Simon
mesh_terms: D000818:Animals; D001665:Binding Sites; D007501:Iron / Q000378:metabolism*; D008543:Melanins / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D008974:Mollusca; D013059:Spectrum Analysis, Raman
chemical_list: D008543:Melanins; C041877:eumelanin; D007501:Iron