Abstract: The immunoreactivities of three rabbit anticalmodulin antibodies with plant and animal calmodulin(CaM) were tested using the techniques of ELISA and immuno-gold electron microscopy. The results showed that the relative affinity of anti-wheat calmodulin antibody(WAb) was greater than that of anti-dintrobenzene-modified porcine brain CaM antibody(D-Ab), and the relative affinity of anti-bovine brain CaM antibody(B-Ab) for wheat CaM was weak The dissociation constants(KD) of CaM antibody and CaM measured by ELISA were: 2.50 × 10-9 mol/L for W-Ab/wheat-CaM, 2.82×10-8 mol/L for D-Ab/wheat CaM, and 1.90×10-8 mol/L for D-Ab/bovine brain-CaM. The affinity of B-Ab for wheat CaM was so Iow that ELISA detection of the KD value was not feasible. Localization of CaM of corn root4ip cells with immuno-gold electron microscopic technique revealed that using the W-Ab probe, the labelled CaM density was greater than using the D-Ab probe, and with B-Ab probe, the density was very low. In quantitation of wheat CaM by competitive ELISA, the detection sensitivity of W-Ab for wheat CaM was higher than that of D-Ab for wheat CaM. These results suggest that the affinity of anti-plant CaM antibody for plant CaM is higher than the affinity of anti-animal CaM antibody for plant CaM. Using anti-plant CaM antibody in the study of plant CaM could raise the sensitivity of immunological detection for plant CaM. The difference in cross-reaction of anti-plant CaM antibodies and anti-animal CaM antibodies with animal CaM and plant CaM was discussed.

Key words: Calmodulin, Anti-calmodulin antibody, Affinity, EL1SA