Lactoglobulin, —, hydrodynamic

Phase boundaries were also developed for p-lactoglobulin, chicken egg albumin, lysozyme, ribonuclease, and trypsin, all at r=100, a weight ratio at which polymer saturation appears to take place (see Discussion section). For each protein, pHcritical was converted to net negative surface charge (Zpr) per unit protein surface area (A), using potentiometric titration curves (26-31) and hydrodynamic radii (32) found in literature. Plots of surface charge density (Zpr/A) vs. I are shown in Figure 3. 

The introduction of succinyl residues producing short-range repulsive forces in place of possible short-range attractive forces in the native molecule resulted in a change of hydrodynamic properties of bovine serum albumin (BSA), bovine y-globulin, and /3-lactoglobulin [3], The succinylated derivatives showed markedly increased intrinsic viscosity and Stokes radius and a decrease of sedimentation coefficient [36,37], These results are compatible only with a considerable increase in the effective volume occupied by the succinylated protein molecule compared to its unreacted counterpart. 

The difficulty of ascertaining the structure of the adsorbed protein is greater for globular proteins. In these cases, the adsorbed layer is much thinner than it is for the caseins, so that layers of B-lactoglobulin appear to be of the order of 1 to 2 nm thiek instead of about 10 nm measured for the easeins (39,90,94). From hydrodynamics and scattering experiments, it is even possible to suggest that the... 

At pH 4.5 and low temperatures, ) -lactoglobulin A associates to form an octamer.A stable dimer (-36,700 daltons) forms at pH values near its isoelectric point of pH 5.2. Results of hydrodynamic measurements, small-angle X-ray scattering, and X-ray crystallography support a structure of the dimer as a prolate ellipsoid with a dyad axis of symmetry, having an overall length of 6.95 nm and a width of 3.6 nm. ... 

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