Abstract: The interaction between dansyl-labeled pollen calmodulin(D-pCaM) and buckwheat pollen peptide analogs was studied in the presence of Ca²⁺. Most peptides in our research can associate with D-pCaMand form peptide-pCaMcomplexes, which changed the fluorescence spectra of D-pCaM. The dissociation constants K_dfor these complexes were determined using fluorescence titration. Peptide BP-13, AMALALKKTGNH₂, had the smallest K_dvalue 4.0 nmol/L, demonstrating the highest affinity for pCaM. In addition to studying the influence of hydrophobicity, propensity of secondary structure and chain length on these peptides abilities to bind pCaM, we have also found that Gly/L-Ala→D-Ala substitution in peptide chains caused great changes in their affinity for pCaM. These results suggest a potentially useful approach to improving the binding ability of peptidic antagonist to CaM. Furthermore, our data provided evidence on the dissimilarity of different CaMs although they have highly-conserved structures. Aprimary study was carried out on the effects of CaM-binding peptides on cellular signal transduction, cell proliferation and growth, showing the participation of CaMin this important cellular life process.

Key words: Pollen calmodulin, Cellular signal transduction, Affinity, Peptide