The Effects of Ce(~3+) and Ce(~4+) on the Stability of Fibroblast GrowthFactor-2

摘要

The interaction between tri or tetravalent cerium ions and basic fibroblast growth factor (FGF-2) at 0.1-6: 1 molar ratio under physiological condition was studied by fluorescence and CD spectrum. The different spectra alterations of FGF-2 induced by Ce(~3+) and Ce(~4+) showed that Ce(~3+) and Ce(~4+) caused different conformational changes of FGF-2 respectively, though both of them destabilized the protein. The instability of FGF-2 in the presence of Ce(~3+) is involved in the oxidation of its free cystein of protein, but that this treatment nearly does not affect the biological activity. As to Ce(~4+), it not only induced the conformational changes of protein but also inhibits its activity in a dose-dependent manner, which could be relative to the electrostatic repulsion between Ce(~4+) and its basic amino acid residues (pl=9.6) or the specific binding of Ce(~4+) to deprotonated amino acid residues. The interesting results would be helpful to investigate the problem of the stability of proteins.