Lectin like properties and differential sugar binding characteristics of C-reactive proteins purified from sera of normal and pollutant induced Labeo rohita

Abstract

Different forms of C-reactive proteins (CRPs) have been purified to electrophoretic homogeneity from the sera of Labeo rohita confined in freshwater (CRP_N) and water polluted with nonlethal doses of cadmium (CRP_Cd) or mercury (CRP_Hg). CRP_N[emsp4 ], CRP_Cd[emsp4], and CRP_Hg show remarkable differences in their electrophoretic mobility but exhibit strong immunological cross reactivity. All these CRPs exhibit variable agglutination properties with erythrocytes from diverse sources in presence of Ca⁺², which could be inhibited by a variety of sugars showing specificity for galactose. Inhibition results show that the potency of galactose as an inhibitor increases about 4 fold in the process of transformation of CRP_N to CRP_Cd and CRP_Hg[emsp4]. In case of CRP_N[emsp4], Gal β (1→1) Gal and oNO₂ phenyl β-Gal show highest inhibitory potency while oNO₂-phenyl β-Gal is the most potent inhibitor for CRP_Cd and CRP_Hg but the potency of Gal β (1 → 1) Gal reduced drastically. 6-phosphate D-Gal and stachyose are 20 times weaker inhibitors than D-Gal for induced CRP mediated agglutination, in contrast, these sugars are only 6 times weaker for CRP_N[emsp4]. Dissociation constants of the binding of CRP_N with phosphoryl choline (PC) and galactose are about 9[emsp4 ]mM and PC binding causes a change in the α and β conformations of these CRPs.