TY - JOUR
T1 - Water molecules in the binding cavity of intestinal fatty acid binding protein
T2 - Dynamic characterization by water 17O and 2H magnetic relaxation dispersion
AU - Wiesner, Silke
AU - Kurian, Elizabeth
AU - Prendergast, Franklyn G.
AU - Halle, Bertil
N1 - Funding Information:
In Lund, we thank Vladimir Denisov, Haukur Jóhannesson, Kristofer Modig, and Eva Thulin for assistance with NMR spectrometers and protein purification. In Rochester, we thank Vladimir Likic, Nenad Juranic, and Slobodan Macura for making available their water-NOE results on ANS-IFABP, and Vladimir Likic for communicating his MD results. This work was supported by the Crafoord Foundation and the Swedish Natural Science Research Council (to B.H.) and by the National Institutes of Health, grant GM 34847 (to F.G.P.).
PY - 1999/2/12
Y1 - 1999/2/12
N2 - 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.
AB - 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.
KW - Cavity
KW - Intestinal fatty acid binding protein
KW - Magnetic relaxation dispersion
KW - Protein hydration
KW - Water residence time
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U2 - 10.1006/jmbi.1998.2490
DO - 10.1006/jmbi.1998.2490
M3 - Article
C2 - 9931262
AN - SCOPUS:0033548262
SN - 0022-2836
VL - 286
SP - 233
EP - 246
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 1
ER -