Dielectric spectroscopy study of myoglobin in glycerol-water mixtures

Soham Roy, Ranko Richert

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Due to the interest in protein dynamics, there are numerous dielectric relaxation studies of proteins in water and in glass-forming aqueous solvents such as glycerol-water mixtures. In the regime of low frequencies, the inevitable dc-conductivity of such systems limits the resolution of dynamics that are slow compared with the solvent relaxation. Solutions of myoglobin in glycerol/water mixtures of various compositions are measured by dielectric spectroscopy in the frequency range from 10 mHz to 10 MHz. The resolution of low frequency modes is improved by two approaches: electrical 'cleaning' and the analysis of the derivative of the real component of permittivity, which shows no direct signature of dc-conductivity. Effects of internal interfacial polarization are also addressed by measuring the same solvents in confinement as well as mixed with glass beads. We find two processes, the structural relaxation of the solvent and the slower rotational mode of the protein, with no indication at even lower frequencies of a dielectric signature of fluctuations associated with protein dynamics.

Original languageEnglish (US)
Pages (from-to)323-329
Number of pages7
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1844
Issue number2
DOIs
StatePublished - Feb 1 2014

Keywords

  • Dielectric relaxation
  • Electrical 'cleaning'
  • Glass transition
  • Interfacial polarization
  • Protein dynamics
  • Solvent dynamics

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology

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