Water molecules in the binding cavity of intestinal fatty acid binding protein: Dynamic characterization by water 17O and 2H magnetic relaxation dispersion

Silke Wiesner, Elizabeth Kurian, Franklyn G. Prendergast, Bertil Halle

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The hydration of intestinal fatty acid binding protein (IFABP) in apo-form and complexed with palmitate, oleate, and 1-anilino-8-naphthalene sulfonate (ANS) has been studied by water 17O and 2H magnetic relaxation dispersion (MRD) measurements. These ligands bind in a large internal cavity, displacing most of the crystallographically identified cavity water molecules. Unlike most other proteins, IFABP gives rise to MRD profiles with two dispersion steps. The low-frequency dispersion yields a correlation time of 7 ns at 300 K, matching the known tumbling time of IFABP. The dispersion amplitude requires only three (apo) or four (holo) long-lived and ordered water molecules (residence time 0.01-4 μS at 300 K). Comparison of MRD profiles from the different complexes indicates that the displaced cavity water molecules are short-lived. The few long-lived (> 10 ns) water molecules required by the MRD data are tentatively assigned to crystallographic hydration sites on the basis of accessibility, positional order, and H-bonding. The amplitude of the high-frequency dispersion corresponds to 10-20 moderately ordered water molecules, with a correlation time of ca. 1 ns that may reflect a transient opening of the cavity required for exchange with external water.

Original languageEnglish (US)
Pages (from-to)233-246
Number of pages14
JournalJournal of Molecular Biology
Issue number1
StatePublished - Feb 12 1999



  • Cavity
  • Intestinal fatty acid binding protein
  • Magnetic relaxation dispersion
  • Protein hydration
  • Water residence time

ASJC Scopus subject areas

  • Virology

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