NMR relaxation investigation of water mobility in aqueous bovine serum albumin solutions

doi:10.1016/0005-2795(76)90267-1

Biochimica et Biophysica Acta (BBA) - Protein Structure

Volume 453, Issue 1, 26 November 1976, Pages 218-232

https://doi.org/10.1016/0005-2795(76)90267-1 Get rights and content

Abstract

T₁ and T₂ dispersion measurements of proton spin relaxation on aqueous solutions of bovine serum albumin as a function of both protein concentration and temperature, covering Larmor frequencies from 3 kHz to 75 MHz, will be presented as a most conclusive test for a three-phase fast-exchange relaxation model. By means of a computer curve fitting of this model to the experimental data, we were able to separate 3 distinct water environments and, in addition, the rotational tumbling of the bovine serum albumin molecules.

The water consists of free, translationally hindered and rotationally bound H₂O molecules with correlation times τ_F ≈ 10⁻¹¹ S, τ_HT ≈ 10⁻⁹ s and τ_HR ≈ 10⁻⁸ S, respectively. This observation indicates a strong, but not directional protein water interaction, and there is no evidence for the existence of “ice like” water. The results from pH variation of the solution and from denaturation of the protein could be fitted with the three-phase model with slightly modified parameters, but without principle changes. The serum albumin molecules were found to undergo slow rotational reorientations with a correlation time, which is greatly affected by the protein concentration, by the temperature of the solution and by denaturation of the protein (τ_PR ≈ 10⁻⁶…10⁻⁷s).

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NMR relaxation investigation of water mobility in aqueous bovine serum albumin solutions

Abstract

Adv. Protein Chem.

Biochim. Biophys. Acta

J. Phys. Chem.

J. Magn. Resonance

Theoret. Experiment. Biophys.

Biophysik

Annu. Rev. Biophys. Bioengin.

J. Polymer Sci.

Z. Angew. Phys.

NMR Basic Principles and Progress

Z. Naturforsch.

Z. Naturforsch.

Ber. Bunsenges. Phys. Chem.

Biophys. J.

Biophys. J.