Influence of allosteric effectors on the heme conformation of dromedary ferrous nitrosylhemoglobin detected by XANES spectroscopy

Agostina Congiu Castellano, Stefano Della Longa, Antonio Bianconi, Mario Barteri, Emilio Burattini, Paolo Ascenzi, Massimo Coletta, Roberto Santucci, Gino Amiconi

Research output: Contribution to journalArticlepeer-review

Abstract

The changes of the Fe heme-active site conformation of dromedary (Camelus dromedarius) nitrosylhemoglobin (HbNO) induced by inositol hexakisphosphate (IHP) and chlofibric acid (CFA) have been studied by using X-ray absorption near-edge structure (XANES) spectroscopy. Structural information has been determined by multiple scattering analysis of the Fe K-edge XANES spectra. The proximal histidine is found to move away from iron centers by about 0.4 Å on the average over the four hemes upon binding of CFA or stoichiometric amount of IHP. In molar excess of polyanion or in the simultaneous presence of IHP, CFA and chloride, the proximal histidine moves back to a position very close to that observed in pure buffer; yet, the structure modulation induced by the allosteric effectors is not completely reversible. Such findings parallel with the functional properties and the spectroscopic (e.g., EPR and absorbance) characteristics of HbNO.

Original languageEnglish
Pages (from-to)119-125
Number of pages7
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume1080
Issue number2
DOIs
Publication statusPublished - Oct 25 1991

Keywords

  • (C. dromedarius)
  • Dromedary hemoglobin
  • Ferrous nitrosylhemoglobin
  • XANES spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology
  • Structural Biology

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