Purification of Calmodulin and Preparation of Immobilized Calmodulin

This chapter focuses on the purification of calmodulin and preparation of immobilized calmodulin. Calmodulin is an acidic, low molecular weight, calcium-modulated protein, which has been isolated from a diverse number of sources, and characterized in terms of its amino acid sequence and biochemical activities. The protein is highly conserved in both structure and function, although, there are quantitative differences in some activator activities among calmodulins. As a consequence, it may be important that functional studies of calmodulin-binding proteins be carried out with calmodulins from the appropriate biological sources. Because calmodulin is a member of a family of closely related calcium-binding proteins that can coexist in the same cell, purification procedures designed to give proteins of high purity are also necessary for many studies. Purification procedures for calmodulins from different sources have appeared in preceding volumes of this series and in the literature. Recent advances in high-performance liquid chromatography (HPLC) and protein sequence analysis, however, have allowed a more detailed characterization of calmodulins.