The heme environment of mouse neuroglobin. Evidence for the presence of two conformations of the heme pocket

Manon Couture, Thorsten Burmester, Thomas Hankeln, Denis L. Rousseau

Research output: Contribution to journalArticle

112 Scopus citations

Abstract

Neuroglobin (Ngb) is a newly discovered oxygen-binding heme protein that is primarily expressed in the brain of humans and other vertebrates. To characterize the structure/function relationships of this new heme protein, we have used resonance Raman spectroscopy to determine the structure of the heme environment in Ngb from mice. In the Fe2+CO complex, two conformations of the Fe-CO unit are present, one of which arises from an open conformation of the heme pocket in which the CO is not interacting with any nearby residue, and the other arises from a closed conformation where a positively charged residue near the CO group stabilizes the complex. For the Fe2+O2 complex, we detect a single vFe-OO stretching mode at a frequency similar to that of oxymyoglobins and oxyhemoglobins of vertebrates (571 cm-1). Based on the Fe-C-O frequencies of the closed conformation of Ngb, a highly polar distal environment is indicated from which the O2 off-rate is predicted to be lower than that of Mb. In the absence of exogenous ligands, a heme pocket residue coordinates to the heme iron, forming a six-coordinate complex, thereby predicting a low on-rate for exogenous ligands. These structural properties of the heme pocket of Ngb are discussed with respect to its proposed in vivo oxygen delivery function.

Original languageEnglish (US)
Pages (from-to)36377-36382
Number of pages6
JournalJournal of Biological Chemistry
Volume276
Issue number39
DOIs
StatePublished - Sep 28 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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