TY - JOUR
T1 - Dielectric spectroscopy study of myoglobin in glycerol-water mixtures
AU - Roy, Soham
AU - Richert, Ranko
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation under Grant No. CHE 1026124 (International Collaboration in Chemistry).
PY - 2014/2
Y1 - 2014/2
N2 - 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.
AB - 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.
KW - Dielectric relaxation
KW - Electrical 'cleaning'
KW - Glass transition
KW - Interfacial polarization
KW - Protein dynamics
KW - Solvent dynamics
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U2 - 10.1016/j.bbapap.2013.11.011
DO - 10.1016/j.bbapap.2013.11.011
M3 - Article
C2 - 24291287
AN - SCOPUS:84890290240
SN - 1570-9639
VL - 1844
SP - 323
EP - 329
JO - Biochimica et Biophysica Acta - Proteins and Proteomics
JF - Biochimica et Biophysica Acta - Proteins and Proteomics
IS - 2
ER -