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Characterization of binding behaviors of Cd2+ to rice proteins

Feng, Wei, Dong, Tiantian, Li, Keqiang, Wang, Tao, Chen, Zhengxing, Wang, Ren
Food chemistry 2019 v.275 pp. 186-192
acetates, cadmium, calcium, citrates, copper, endothermy, iron, metal ions, pH, zinc
In this paper, for the first time the binding behavior of cadmium (Cd2+) to rice proteins (RPs) was studied. The results showed that the equilibrium of binding was reached within 30 min at 303 K with a maximum binding amount (q) of 15.26 mg/g, and the pH was an important factor positively influencing q. At both 308 K and 313 K, the binding of Cd2+ to RPs belonged to spontaneous, endothermic interactions with high-affinity, assigned to a multidentate coordination. Except for acetate, all the investigated competing coordination agents, such as edetate, pyrophosphate and citrate, showed inhibitory effects on RPs-Cd2+ binding, and edetate seemed to be the most effective one. At pH 6.5, calcium, copper and zinc began to restrict RPs-Cd2+ binding when the metal ion concentration reached 500 mg/kg, and the decreasing of pH would strengthen the inhibitory effects of the investigated metal ions including ferric ions.