Lysozyme solutions, water relaxation

Fullerton et al. (1986) measured H spin-lattice relaxation during dehydration of lysozyme solutions to a nearly dry state, and during rehydration of lyophilized lysozyme powder by isopiestic equilibration and, for high hydration levels, by titration with water. Breaks in the NMR response were found at 0.055, 0.22-0.27, and 1.22-1.62 h (Fig. 19 shows the two higher hydration discontinuities in slope). Estimates of the water correlation times are 10 , 2 x 10 , and 5 X 10 sec, respectively, for the three classes of water defined by the breaks. The 0.055... 

The spin-lattice relaxation time, T, measurements of labeled water in aqueous lysozyme solution were made by the inversion-recovery pulse sequence(7r-T-7r/2). The relationship between the signal intensity, M x), at any x and T is expressed by... 

Fig. 19. A dehydration from dilute solution study of the spin-lattice relaxation rate (l/r,) versus concentration [mass solute/mass water (Ms/M) = A ] for six different initial concentrations of lysozyme O, 0.5 g/ml A, 1.0 g/ml , 1.5 g/ml V, 2.0 g/ml 0. 2.5 g/ml and x, 5.0 g/ml. The lack of dependence on inidal concentration shows that equilibration time is not an important parameter. From Fullerton et al. (1986).

Relaxation Measurements. NMR measurements have been used to examine water-protein interactions in solution and in hydrated powders (2). Hilton et al (24) have shown that the motional properties of water in partially hydrated powders of lysozyme are best characterized as those of a viscous liquid. Dielectric relaxation spectra of water in lysozyme powders (28) distinguish... 

Other studies included the investigation of the stabilizing effect of sorbitol on hen egg white lysozyme and the use of the self-diffusion coefficient, D, to follow the solution and aggregative properties of lysozyme at different pH, temperature, and protein and salt concentrations. The properties of frozen ovalbumin solutions were studied by NMR relaxation spectroscopy. It is known that the functional properties of muscle proteins are affected by protein interactions with ions, and NMR was used to assess protein/water, protein/salt, and protein/protein interactions in myofibrillar protein solutions. Previous X-ray and NMR studies on collagen and peptides were reviewed by Mayo and, more recently, such types of system were characterized by high-resolution H and C NMR. °0 The structure, hydration state, and nature of the interactions between water and gelatin were determined by time domain NMR. ... 

If the lifetime of the excited state of the conjugates is the same the quantity 0 is proportional to the mean rotational relaxation time. The 0 values obtained with human and bovine albumin, ovalbumin, fumarase, lysozyme, insulin, G actin, and growth hormone protein are in agreement with the accepted estimates of size derived by sedimentation and diffusion and by other methods. In most cases the observations were carried out in water solutions at temperatures from 4° to 60 and the values of po obtained by extrapolation agreed very well with those directly observed in a solution of the conjugate in 60% sucrose at 2 . The latter fact allows the conclusion that any other existent relaxation... 

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