To further investigate the role of calcium in Daptomycin activity, studied the differences in calcium chelation between Daptomycin and its close derivative Kynomycin (methylated on the Kynurenine residue) . Ca 2+induced oligomerization is a fundamental step determining Daptomycin activity and derivatives with improved Ca 2+ chelation abilities may be more effective in terms of killing activity. The methyl-Kynurenine, being more lipophilic than Kynurenine, tightly interacts with tryptophan and the lipid tail and these hydrophobic interactions improve the stability of oligomers. The possibility of exploring such subtle modifications (only one methyl group in this case) is an attractive path for the optimization of existing molecules.