Collect. Czech. Chem. Commun. 1991, 56, 3028-3031

Circularly polarized luminiscence as a probe of metal ions binding sites in calmodulin

Nursen Coruh and James P. Riehl*

Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121, U.S.A.


Circularly polarized luminiscence (CPL) from dilute solutions of Tb(III) bound to the Ca-binding protein calmodulin is reported. The dissymmetry ratio, gem, at 543.5 nm can be monitored as a function of equivalents of metal ion concentration. Competitive and consecutive addition of Ca(II) versus Tb(III) yield results which are consistent with previous results that suggest that Tb(III) and Ca(II) have a preferred affinity for different metal-ion binding sites in this protein.