Wang C L, Aquaron R R, Leavis P C, Gergely J
Eur J Biochem. 1982 May;124(1):7-12. doi: 10.1111/j.1432-1033.1982.tb05900.x.
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.
通过使用三价镧系离子作为Ca2+的类似物，对钙调蛋白的金属结合特性进行了研究。与在这项工作进行期间发表的一份报告一致[Kilhoffer, M.-C., Demaille, J. G., and Gerald, D. (1980) FEBS Lett. 116, 269 - 272]，我们发现位点I和II是高亲和力位点，而位点III和IV是Tb3+的低亲和力位点。竞争实验表明，相同的结合偏好也适用于Ca2+。在用两种酪氨酸残基之一进行选择性硝化的钙调蛋白中，我们发现，尽管两个酪氨酸基团都可以将能量转移到结合的Tb3+，但只有Tyr-138的荧光对金属结合敏感。使用激光直接激发结合的Eu3+离子表明，所有四个位点都具有非常相似的微环境。这些研究表明，钙调蛋白的结合特性与同源蛋白肌钙蛋白C的不同。
