Enhanced heme accessibility in horse heart mini-myoglobin: Insights from molecular modelling and reactivity studies

Fabio Polticelli, Veranika Zobnina, Chiara Ciaccio, Giampiero De Sanctis, Paolo Ascenzi, Massimo Coletta

Research output: Contribution to journalArticlepeer-review

Abstract

Mini-myoglobin (mini-HHMb) is a fragment of horse-heart myoglobin (HHMb) considered to be the prototype of the product encoded by the central exon of the HHMb gene. For this reason, mini-HHMb has been studied extensively showing that carbonylation and oxygenation properties of the ferrous form are similar to those of the full-length protein, while kinetics and thermodynamics of azide binding to the ferric form are significantly different from those of HHMb. To analyze the structure-function relationships in mini-HHMb and the role of conformational fluctuations in ligand accessibility, the molecular model of mini-HHMb has been built and refined by molecular dynamics simulations, and analyzed in parallel with that of full length HHMb. Moreover, imidazole binding parameters of ferric mini-HHMb and HHMb have been determined. Furthermore, structural data of ferric mini-HHMb and HHMb have been correlated with the imidazole and previously determined azide binding properties. Present results indicate that, despite the extensive trimming, the heme-α-helices E-F substructure is essentially unaltered in mini-HHMb with respect to HHMb. However, the heme-Fe atom displays an enhanced accessibility in mini-HHMb, which may affect both ligand association and dissociation kinetics.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume585
DOIs
Publication statusPublished - Nov 1 2015

Keywords

  • Mini-myoglobin
  • Molecular modelling
  • Protein matrix tunnels
  • Reactivity properties
  • Structure

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology
  • Medicine(all)

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