A- Lactalbumin

The elution volume, F/, and therefore the partition coefficient, is a function of the size of solute molecule, ie, hydrodynamic radius, and the porosity characteristics of the size-exclusion media. A protein of higher molecular weight is not necessarily larger than one of lower molecular weight. The hydrodynamic radii can be similar, as shown in Table 4 for ovalbumin and a-lactalbumin. The molecular weights of these proteins differ by 317% their radii differ by only 121% (53). 

WJ Browne, ACT North, DC Phillips, K Brew, TC Vanaman, RC Hill. A possible three-dimensional stnicture of bovine a-lactalbumin based on that of hen s egg-white lysozyme. J Mol Biol 42 65-86, 1969. 

The details of many all-atom unfolding simulation studies have been summarized in several reviews [17,46,47]. These studies include unfolding simulations of a-lactalbumin, lysozyme, bovine pancreatic trypsin inhibitor (BPTI), barnase, apomyoglobin, [3-lacta-mase, and more. The advantage of these simulations is that they provide much more detailed information than is available from experiment. However, it should be stressed that there is still only limited evidence that the pathways and intermediates observed in the nanosecond unfolding simulations correlate with the intermediates observed in the actual experiments. 

Grinberg, V.Y., Grinberg, N.V., Burova, T.V., Dalgalarrondo, M., and Haertle, T., Ethanol-induced conformational transitions in holo-a-lactalbumin Spectral and calorimetric studies. Biopolymers, 46(4), 253-265, 1998. 

The influence of pH, ionic strength, and protein concentration on the extraction of a-lactalbumin and 3-lactoglobulin from an aqueous solution with water/AOT/isooctane microemulsions and their separation has been reported [168],... 

FIGURE 5.1 Rapid molecular simulations of the apoprotein form of a-lactalbumin in vacuo, showing the native holo state and the effect of simulations at 5 and 298 K of the apoform (Farrell et ai, 2002). 

Gezimati, J., Creamer, L. K., and Singh, H. (1997). Heat-induced interactions and gelation of mixtures of p-lactoglobulin and a-lactalbumin. /. Agric. Food Chem. 45,1130-1136. 

These assumptions were confirmed by the electrophoresis study of the washed creams. Electrophoresis of purified fat globules is a convenient method to characterize and quantify proteins adsorbed at the oil-water interface [35]. Electrophoretic data indicate that no casein, nor whey proteins, were adsorbed at the surface of raw-milk fat globule. Upon homogenization, caseins adsorbed preferentially at the lipid-water interface. In this case, bound a-lactalbumin accounted for 16% of the total interfacial proteins. Heat treatment also induced the interaction of proteins with the fat globules. The amount of bound proteins (per mg of lipids) for heated raw milk was half that for homogenized milk. 

The six major proteins of milk, asl-, o s2-, and /c-casein, jS-lactoglobulin, and a-lactalbumin, contain at least one tryptophan residue [57], the fluorescence of which allows the monitoring of the structural modifications of proteins and their physicochemical environment during the coagulation processes. Emission fluorescence spectra of the protein tryptophanyl residues were recorded for the milk coagulation kinetics induced by... 

Weinbrenner, W. F. and Etzel, M. R., Competitive adsorption of a-lactalbumin and bovine serum albumin to a sulfopropyl ion-exchange membrane, J. Chromatogr. A, 662, 414, 1994. 

Rush, R. S., Cohen, A. S., and Karger, B. L., Influence of column temperature on the electrophoretic behavior of myoglobin and a-lactalbumin in high-performance capillary electrophoresis, Anal. Chem., 63, 1346, 1991. 

Bovine a -lactalbumin (BLA) is a protein whose structure appears to be unusually malleable and, as such, has been the focus of many studies of what is termed the molten globule transition. At low pH, BLA expands and is said to lose tertiary structure, but it maintains substantial secondary structure in a partial unfolding transition (molten globule... 

Fig. 36. Far-UV (upper panel) and near-UV (lower panel) CD spectra of guinea pig a-lactalbumin. Native state, pH 7 (—) A state, pH 2 ( ) unfolded state, 9 M urea, pH 2...

Fig. 37. Difference CD spectrum (native-molten globule) in bovine a-lactalbumin ( ). Derivedfrom data of Kuwajima et al (1985) for native (—) and molten globule ( ) forms. 

O Keefe, E.T., Mordick, T., and Bell, J.E. (1980) Bovine galactosyltransferase Interaction with a-lactalbu-min and the role of a-lactalbumin in lactose synthase. Biochemistry 19, 4962-4966. 

---