Binding Sites of La~(3 ) on Camodulin

ＢｉｎｄｉｎｇＳｉｔｅｓｏｆＬａ３＋ｏｎＣａｍｏｄｕｌｉｎ＊ＦｅｎｇＹｕｐｉｎｇ（冯玉萍），ＹｕａｎＨａｏｄａｎ（袁浩丹）＋，ＺｈｏｕＹｕｘｉａｎｇ（周玉祥）＋，ＮｉｎｇＹｏｎｇｃｈｅｎｇ（宁永成），ＺｈａｎｇＲｉｑｉｎｇ（张日清）＋Ｄｅｐａｒｔｍｅ...

Binding Sites of La 3 on Camodulin *

Calmodulin (CaM) is a multifunctional Ca 2 binding regulatory protein with very important physiological functions. The properties of lanthanides (La 3 ) are very similar to Ca 2 .Their activity in living systems is usually related to competition with Ca 2 . Therefore, the study of the interaction between lanthanides and CaM provides evidence for uncovering the functional mechanism of La 3 in the Ca 2 CaM enzyme system.In this report the coordination numbers and the binding sites of La 3 on CaM were studied by using ion titration with one and two dimensional NMR. Their interactional mechanism was also discussed. After considering the effects of La 3 on the chemical shift and on the intensity of the resonance peaks of Tyr 99, His 107 and Phe residues in 1H NMR , and after considering the effects on the correlation peaks in the 2D COSY NMR, it was concluded that the first La 3 was bound near Tyr 99 and His 107 residues,i.e., near binding site III of Ca 2 on CaM. This means the first La 3 was bound the C terminal of CaM.The second and third La 3 might have been bound on the CaM N terminal.