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

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), CRP(Cd), 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). In case of CRP(N), Gal beta(1 --> 1) Gal and oNO2 phenyl beta-Gal show highest inhibitory potency while oNO2-phenyl beta-Gal is the most potent inhibitor for CRP(Cd) and CRP(Hg) but the potency of Gal beta(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). Dissociation constants of the binding of CRP(N) with phosphoryl choline (PC) and galactose are about 9 mM and PC binding causes a change in the alpha and beta conformations of these CRPs.