Metal‐Binding Properties of Calmodulin

作者：Chih‐Lueh Albert Wang, R Aquaron, Paul C. Leavis, John S. Gergely · 发表于：European Journal of Biochemistry · 年份：1982 · 被引用次数：98 · 研究领域：Lanthanide and Transition Metal Complexes、Protein Interaction Studies and Fluorescence Analysis、Mass Spectrometry Techniques and Applications

Metal-binding properties of calmodulin have been studied by using trivalent lanthanide ions as analogs of Ca2+. In agreement with a report published as this work was in progress [Kilhoffer, M.-C., Demaille, J. G., and Gerald, D. (1980) FEBS Lett. 116, 269-272] we found that sites I and II are the high-affinity sites, while sites III and IV are the low-affinity sites for Tb3+. Competition experiments suggest the same preference in binding also applies to Ca2+. With calmodulin selectively nitrated at either of the two tyrosine residues we found that, although both tyrosine groups can transfer energy to the bound Tb3+, the fluorescence of only Tyr-138 is sensitive to metal binding. Direct excitation of bound Eu3+ ions using a laser indicates that all four sites possess very similar microenvironments. These studies demonstrate that the binding properties of calmodulin are different from those of the homologous protein troponir C.