CaM

Lyophilized. Lyophilized from 10 mM sodium phosphate buffer, 5% sucrose, pH 7.0. AVOID FREEZE/THAW CYCLES. Calmodulin (CaM) purified from wheat germ (Triticum aestivum). Wheat germ calmodulin is unique in that it contains cysteine at position 26 (Cys²⁶), which is in contrast to mammalian CaM that does not possess this residue. The single SH moiety on Cys²⁶ makes this CaM preparation ideal for applications requiring both calmodulin activation and residue specific tagging. The sulfhydryl can be labeled using SH-reactive protein-modification reagents like fluorescent maleimide derivatives. Additionally, wheat germ CaM contains only a single tyrosine residue (Tyr¹³⁸), compared to mammalian CaM that has two tyrosine residues, which can serve as a monospecific C-terminal labeling site. Using Cys²⁶ and Tyr¹³⁸ allow wheat germ CaM to be independently derivatized at both the N- and C-termini making it a useful tool for structural, proteomic biomarker discovery and protein-protein interaction studies. Wheat germ CaM also contains no tryptophan residues, resulting in a distinctive absorbance spectrum when compared to mammalian CaM sequences. Specific activity: ≥ 35,000 U/mg protein. One unit is defined as the amount of calmodulin that will stimulate 0.01 unit of 3'5'-cyclic nucleotide phosphodiesterase to 50% of the maximum activity of the enzyme when saturated with CaM in the presence of 100 µM Ca²⁺ in a 3 ml reaction volume at 30°C, pH 7.5. Purity: >98% by SDS-PAGE.

Ref.: Strasburg, G.M., et al. 1988. J. Biol. Chem. 263, 12161.