Chemical properties of thiolated and succinylated caseins

Abstract

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, asi-and 0-casein bands remained while x-and as2-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.

Effect of maleylation on physicochemical and functional properties of rapeseed protein isolate

“…The band observed at 1401 cm −1 (attributable to C = O bond of ionized carboxyl (COO − ) group) became more pronounced after modification with respect to the control. This is because acylation introduces additional carbonyl groups (Strange et al 1993). With an increasing extent of maleylation, a sharp peak at~861 cm −1 and a shoulder at 1185 cm −1 , implying the presence of CH bend of alkene (or ring substitution) and acyl C-O, respectively, became more prominent especially above 0.4MA (Fig.…”

“…Confirmation of this explanation is given by FTIR, GPC and intrinsic fluorescence of these samples (discussed later). Despite the presence of high amount of randomness and protein dissociation in 0.6MA and 0.8MA, the drop in hydrophobicity after exhaustive acylation may be due to the dense distribution of negatively charged maleyl residues, inhibiting Coomassie Blue dye (probe used for S 0 measurement) from approaching and binding to the exposed hydrophobic moieties on the protein surfaces (Strange et al 1993). Similar behavior has been reported also for 1-anilino-8-naphthalenesulfonic acid (fluorescence probe for S 0 measurement) in modified soy protein hydrolyzates (Achouri and Zhang 2001) and acylated kidney bean protein (Yin et al 2010).…”

Influence of succinylation on the conformation of yak casein micelles

“…Succinylation, which is one of frequently used modification method, enhances solubility, emulsification, foaming characteristics and other functional properties of protein (Gruener & Ismond, 1997;Kohara, Kanei, & Nakajima, 2001;Mirmoghtadaie, Kadivar, & Shahedi, 2009;Yang, Shi, et al, 2014). Succinylation has been shown to improve the functional properties of cow caseins (Lakkis & Villota, 1992;Strange, Holsinger, & Kleyn, 1993;Yang, Shi, et al, 2014).…”

Modification of egg albumen to improve thermal stability

“…Using the same mechanism, succinylation of proteins can also improve the thermal stability of proteins and other functional properties of egg white, casein, and soy proteins. [42][43][44] Egg albumen has been succinylated with succinic anhydride (SA), showing a visual improvement in turbidity with an increase in degree of modification, based on free amine (27,45, to 100% modification). 42 Its thermal stability was increased.…”