Pentacoordinate hemin derivatives in sodium dodecyl sulfate micelles: Model systems for the assignment of the fifth ligand in ferric heme proteins

Alberto Boffi, Tapan Kanti Das, Stefano Della Longa, Carla Spagnuolo, Denis L. Rousseau

Research output: Contribution to journalArticle

81 Scopus citations


Ferric iron protoporhyrin IX derivatives in SDS micelles have been investigated by means of visible absorption, resonance Raman, and XANES spectroscopies to establish specific correlations between the marker bands of the pentacoordinate derivatives obtained from the three different techniques. Hydroxyl and 1,2-dimethyl imidazole coordinated hemins display the typical spectroscopic marker bands of a pentacoordinate high-spin ferric iron derivative in both Raman and XANES spectra. In turn, the optical absorption spectra of these two derivatives are very different. This difference is in line with the assignment of hydroxyl as the fifth coordination ligand to free hemin in SDS micelles, as demonstrated by the isotopic shift of the frequency of Fe-OH bond with H218O. The present assignments are relevant to the identification of the coordination state and the nature of the fifth ligand in ferric heme proteins.

Original languageEnglish (US)
Pages (from-to)1143-1149
Number of pages7
JournalBiophysical Journal
Issue number2
StatePublished - Aug 1999


ASJC Scopus subject areas

  • Biophysics

Cite this