Chemical properties of thiolated and succinylated caseins
1993
Strange, E.D. | Holsinger, V.H. | Kleyn, D.H.
Gelation of casein may be improved by introduction of functional groups that are both hydrophilic and capable of forming disulfide bonds. Thiolated whole caseins were prepared with S-acetylmercaptosuccinic anhydride at four concentrations to study chemical properties related to gelation. Succinylated samples were prepared for comparison. Degree of modification was determined by decrease in reactive lysine content. Urea-PAGE showed decreased positive charge for modified proteins as degree of modification increased. In addition, alpha-S1- and beta-casein bands remained while kappa- and alpha-S2-casein bands disappeared compared to whole native casein. SDS-PAGE without added mercaptoethanol indicated formation of intermolecular disulfide bonds in the thiolated derivatives. All modified caseins precipitated in the presence of Ca2+, but the concentration needed increased with degree of modification. Thiolated caseins were less soluble in the presence of high Ca2+ levels than succinylated or native caseins. Changes observed indicate successful introduction of groups that may enhance gelation.
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