Hydration analysis of Pseudomonas aeruginosa cytochrome c551 upon acid unfolding by dielectric relaxation spectroscopy

Tetsuichi Wazawa, Takashi Miyazaki, Yoshihiro Sambongi, Makoto Suzuki

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Dielectric relaxation (DR) study was performed to reveal the hydration change of Pseudomonas aeruginosa ferric cytochrome c551 (PA c551) in dilute aqueous solutions upon the acid unfolding which undergoes a two-state transition. The DR spectrum of a small spherical region containing a PA c551 molecule and its surrounding water shell was derived from the solution and solvent spectra by dielectric mixture theories. The derived spectrum was well-fitted with a sum of a Debye relaxation component (C1) with a DR frequency around 4.7. GHz and the bulk solvent component (CB). Upon acid unfolding, the DR amplitude of CB decreased with decreasing pH in an inverse manner to that of C1, while the total DR amplitude was almost constant. It indicates that C1 is due to the hydration water of PA c551. Little change in the DR frequency of C1 and a 1.7-fold increase in hydration number were observed.

Original languageEnglish
Pages (from-to)160-169
Number of pages10
JournalBiophysical Chemistry
Volume151
Issue number3
DOIs
Publication statusPublished - 2010 Oct

Keywords

  • Acid denaturation
  • Constrained water
  • Debye relaxation
  • Dielectric dispersion
  • Loosely-bound water
  • Two-state transition

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Organic Chemistry

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