Thermodynamic analysis of hydration in human serum heme-albumin

Simona Baroni, Giorgio Pariani, Gabriella Fanali, Dario Longo, Paolo Ascenzi, Silvio Aime, Mauro Fasano

Research output: Contribution to journalArticlepeer-review

Abstract

Ferric human serum heme-albumin (heme-HSA) shows a peculiar nuclear magnetic relaxation dispersion (NMRD) behavior that allows to investigate structural and functional properties. Here, we report a thermodynamic analysis of NMRD profiles of heme-HSA between 20 and 60 °C to characterize its hydration. NMRD profiles, all showing two Lorentzian dispersions at 0.3 and 60 MHz, were analyzed in terms of modulation of the zero field splitting tensor for the S = 5/2 manifold. Values of correlation times for tensor fluctuation (τv) and chemical exchange of water molecules (τM) show the expected temperature dependence, with activation enthalpies of -1.94 and -2.46 ± 0.2 kJ mol-1, respectively. The cluster of water molecules located in the close proximity of the heme is progressively reduced in size by increasing the temperature, with ΔH = 68 ± 28 kJ mol-1 and ΔS = 200 ± 80 J mol-1 K-1. These results highlight the role of the water solvent in heme-HSA structure-function relationships.

Original languageEnglish
Pages (from-to)385-389
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume385
Issue number3
DOIs
Publication statusPublished - Jul 31 2009

Keywords

  • Ferric human serum heme-albumin
  • Heme-protein hydration
  • Human serum albumin
  • NMR relaxation

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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