Calmodulin from bovine testes was purchased as a lyophilised power (P1431 Sigma, UK) and stored in aliquots at -20ºC as a 40 µM stock solution in 10 mM ammonium acetate. For analysis, stock solution was diluted in 10 mM ammonium acetate to a final concentration of 5 µM. Melittin from honey bee venom (M2272 Sigma, UK) and Calmodulin-dependent Protein Kinase II fragment 290-309 (C4926 Sigma, UK) were stored as stock solutions at 1 mM in 10 mM ammonium acetate at -20 ºC. For all ligand binding experiments the peptides were added to calmodulin at a final concentration of 7.5 µM, giving a 1:1.5 protein:ligand ratio.