Interactions betweenk-Casein andβ-Lactoglobulin: Effects of Anions on Covalent Stabilization of the Complex

Interaction between .kappa.-casein and .beta.-lactoglobulin: possible mechanism

“…In other words, k-C/ß-Lg interactions in heated milk are greatest at lower holding temperatures at which the tendency for self-association of -C is less and hence more monomeric -C may be available to react with ß-Lg. We observed a similar trend with a heated k-C/ß-Lg mixture (Haque et al, 1987). It should however be emphasized that the stoichiometry of the reaction is based on the HPLC elution profile of the various fractions and the staining intensity of the components of the different bands following SDS-PAGE of these fractions.…”

“…The elution positions of A4, A3, A2, and indicated that they represent a tetramer, trimer, dimer, and monomer of either -C or /3-Lg assuming a common molecular weight of 18500. It should be emphasized that the elusion position may be influenced by the changes in the hydrodynamic radius of the molecules especially when elusion conditions are changed (Haque et al, 1987). However, the marked difference in the elusion positions of A2, A3, and A4 and appearance also of the on addition of 10 mM 2-ME indicated that these fractions represented different states of molecular association.…”

“…The first stage in the thermal interaction involved the formation of the urea-stable A3 (/3-Lg3) complex that was less reactive with -C in the presence of Ca2+. In the presence of EGTA, a more reactive A3 complex interacted with one molecule of -C to give the A4 complex (Figure 5). The size/shape of the A3 complex affects the rate constant of A4 formation (Haque et al, 1987). Heating at 70 °C increased the rate of A4 formation by increasing the potential for hydrophobic interaction.…”