In order to reduce the immunoreactivity of sarcoplasmic calcium-binding protein (SCP), site-directed mutations were used to replace key amino acids in the conformational epitopes and calcium-binding sites. The mutant SCPs (mSCPs) were expressed in Escherichia coli, and their immunoreactivities were analyzed using iELISA and basophil activation assays. Furthermore, the structural changes of mSCPs were determined from the circular dichroism spectra. The iELISA results showed that mSCPs could effectively inhibit the binding of wild-type SCP (wtSCP) to sensitive serum, with inhibition rates that reached 90%. Moreover, mSCPs could downregulate the expression levels of CD63 and CD203c on the basophil surface. Compared with wtSCP, the peak values were significantly changed, and the calcium binding ability was impaired, which explained the decline in immunoreactivities of the mSCPs. All of the data confirmed that this approach was effective in reducing the immunoreactivity of SCP and could be applied to other shellfish allergens.

a b s t r a c t Selenium (Se) is one of contaminants required to be regulated during drinking water treatment, however, little information has been collected to date regarding Se removal by coagulation. In this study, the performance of Se removal by coagulation has been evaluated with respect to the dependence on Se species, coagulant type, water pH and interfering ions. The results showed that a Fe-based coagulant was much more efficient than Al-based coagulants in Se removal. The removal of selenite (Se(IV)) by coagulation was much more pronounced than that of selenate (Se(VI)). With an FC dosage of more than 0.4 mM Fe/L, Se(IV) removal efficiency of more than 98% could be achieved when the initial Se(IV) concentration was 250 lg/L. For Al-based coagulants (AlCl 3 (AC) and polyaluminum chloride (PACl)) Se removal efficiency was positively correlated with the content of Al 13 species during the coagulation process. Adsorption onto hydroxide flocs was the most active coagulation mechanism for Se removal and precipitation also played specific roles at low dosage, especially for Se(IV) removal and with Fe coagulant. High coagulant dosage and weakly acidic pH could enhance the formation of hydroxide flocs having more active adsorption sites and high zeta potential, and thus favored Se removal. These findings are important to understand the efficiency and mechanisms of Se removal by coagulation.

a b s t r a c tThe effect of Al speciation on arsenate [As(V)] removal during coagulation process was investigated from the viewpoint of Al hydrolysis species transformation. The As(V) removal efficiency of preformed Al 13 was compared with that of in situ formed Al 13 considering various Al dosages and pH values. The mechanisms of As(V) removal by Al salt coagulation were explored, and adsorption ability of the flocs formed from Al 13 species were evaluated. The results showed that As(V) removal efficiency was positively correlated with the content of Al 13 species during coagulation process. Weak acidic condition (pH 5-7) is the optimal pH range to remove As(V) because Al 13 species, especially for AlCl 3 , is largely in situ formed from the transformation of monomeric Al species. Through regulating Al speciation, pH adjustment could improve As(V) removal and AlCl 3 could benefit most from this. In contrast, the improvement induced by pH control for polyaluminum (PACl) was slighter because Al speciation of PACl was less dependent upon water pH. This present study confirmed that adsorption on formed hydroxide flocs was the most active mechanism for As(V) removal by Al based coagulants. The flocs generated from in situ formed Al 13 presented better As(V) adsorption ability than the flocs generated from preformed Al 13 . These findings are important to understand the coagulation mechanisms of arsenic removal by Al based coagulants.