Characterization of heat-induced aggregates of beta-lactoglobulin, alpha-lactalbumin and bovine serum albumin in a whey protein concentrate environment
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Date
2001
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Cambridge University Press
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Abstract
Bovine b-lactoglobulin (b-lg), a-lactalbumin (a-la) and bovine serum
albumin (BSA), dispersed in ultra®ltration permeate, that had been prepared from
whey protein concentrate solution (100 g}kg, pH 6±8), were heated at 75 °C. The
consequent protein aggregation was studied by one-dimensional (1D) and twodimensional
(2D) polyacrylamide gel electrophoresis (PAGE). When 100 g b-lg}kg
permeate solution was heated at 75 °C, cooled and examined, large aggregates were
observed. These aggregates were partially dissociated in SDS solution to give
monomers, disulphide-bonded dimers, trimers and larger aggregates. When mixtures
of b-lg and a-la or BSA were heated, homopolymers of each protein as well as
heteropolymers of these proteins were observed. These polymer species were also
observed in a heated mixture of the three proteins. Two-dimensional PAGE of
mixtures demonstrated that these polymers species contained disulphide-bonded
dimers of b-lg, a-la and BSA, and 1:1 disulphide-bonded adducts of a-la and b-lg, or
BSA. These results are consistent with a mechanism in which the free thiols of heattreated
b-lg or BSA catalyse the formation of a range of monomers, dimers and
higher polymers of a-la. It is likely that when whey protein concentrate is heated
under the present conditions, BSA forms disulphide-bonded strands ahead of b-lg
and that a-la aggregation with b-lg and with itself is catalysed by the heat-induced
unfolded BSA and b-lg.
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Keywords
β-Lactoglobulin, α-Lactalbumin, Bovine serum albumin, Heat-induced aggregation, Beta-lactoglobulin, alpha-lactalbumin
Citation
Havea, P.; Singh, H.; Creamer, L. K. (2001). Characterization of heat-induced aggregates of beta-lactoglobulin, alpha-lactalbumin and bovine serum albumin in a whey protein concentrate environment. Journal of Dairy Research. Vol. 68, No. 3, pp. 483-497.