USE OF Tb~(3+) AS A LUMINESCENT PROBE TO STUDY THE INTERACTION OF CALMODULIN WITH ITS ANTAGONISTS
Tb~(3+)作为荧光探针研究钙调蛋白与拮抗药物的相互作用

A simple, rapid and sensitive method determining the binding sites of antagonists on calmodulin was introduced.Studies on the intrinsic fluorescence of calmodulin have shown that Tb3+ can efficiently bind to the Ca2+ -binding sites on calmodulin and then induce conformational changes similar to those of Ca2+. Because each of domains III and IV on calmodulin has one tyrosine, the binding of Tb3+ to calmodulin was followed by obvious increase of Tb3+ fluo-rescence at 490 nm and 545nm, which was caused by exciting the calmodulin tyrosine at 280 nm with energy transfer from tyrosine to Tb3+ . By studing the effect of calmodulin antagonists on this fluorescence, it was found that the binding sites of TEP were located on the C-terminal part of calmodulin which contains the domains III and IV; whereas the binding sites of jujuboside A were located on the N-terminal part which contains the domains I and II.