Investigation of protein hydration by proton spin relaxation time measurements.

Summary Spin-lattice relaxation times T1 in aqueous solutions of dialysed egg white were measured for concentrations between 4.5 and 9.3 wt. % in the magnetic field range corresponding to proton Larmor frequencies from 0.01 to 160 MHz. A strong dependence of T1 on the magnetic field begins at approx. 0.5 MHz. It can be described by a log-Gauss distribution of rotational correlation times in the solvation layer with the maximum at 1.52·10−9 sec. The greater part of the distribution lies below the correlation time for the reorientation of the ovalbumin molecule itself. This means that the adsorbed water molecules have some freedom of motion with respect to the protein molecule. The width of the distribution is somewhat dependent on the concentration. This paper also contains the results of neutron activation, spectrochemical analysis and EPR measurements, which show that the amount of paramagnetic ions present in samples of protein solutions cannot be responsible for the decrease of T1 with respect to pure water.

[1]  J. Glasel.  Magnetic Relaxation Studies of Protein Solvation , 1968, Nature.

[2]  S. Meiboom,et al.  NUCLEAR MAGNETIC RESONANCE STUDY OF THE PROTON TRANSFER IN WATER , 1961 .

[3]  W. Anderson,et al.  PROTON RELAXATION TIMES IN H$sub 2$O-D$sub 2$O MIXTURES , 1956 .

[4]  W. Brittin,et al.  Nuclear Magnetic Resonance Studies in Multiple Phase Systems: Lifetime of a Water Molecule in an Adsorbing Phase on Silica Gel , 1957 .

[5]  S. H. Koenig,et al.  Nuclear magnetic relaxation dispersion in protein solutions. II. Transferrin. , 1969, The Journal of biological chemistry.

[6]  H. Pfeifer,et al.  Die Frequenzabhängigkeit des rotatorischen und translatorischen Anteils der kernmagnetischen Relaxation in Flüssigkeiten , 1966 .

[7]  F. Noack,et al.  Kernmagnetische Relaxation und Korrelation in Zwei-Spin-Systemen , 1964 .

[8]  H. A. Resing.  Apparent Phase—Transition Effect in the NMR Spin—Spin Relaxation Time Caused by a Distribution of Correlation Times , 1965 .

[9]  H. C. Torrey.  Nuclear Spin Relaxation by Translational Diffusion , 1953 .

[10]  E. Purcell,et al.  Relaxation Effects in Nuclear Magnetic Resonance Absorption , 1948 .

[11]  E. Ragozzino.  Proton spin-lattice relaxation in solutions of glycogen in water , 1966 .

[12]  K. Kraus,et al.  Anion Exchange Studies. VI.1,2 The Divalent Transition Elements Manganese to Zinc in Hydrochloric Acid , 1953 .

[13]  J. Hennel,et al.  Proton Magnetic Relaxation and Protein Hydration , 1963, Nature.

[14]  T. M. Connor.  Distributions of correlation times and their effect on the comparison of molecular motions derived from nuclear spin-lattice and dielectric relaxation , 1964 .

[15]  I. Solomon.  Relaxation Processes in a System of Two Spins , 1955 .