The tamandarin and didemnin families of cyclodepsipeptides have shown impressive antitumor and antiviral biological activity, yet their mechanism of action is unknown. Previous affinity chromatography studies have focused only on the macrocyclic portion of the molecule and have excluded the side chain moiety, which has been shown to be important for the biological activity. [Lys]³ Tamandarin B was designed to have the affinity ligand attached to the terminal nitrogen of the lysine residue, allowing an intact side chain. This attachment point is far removed from the side chain and maintains the shape and size of the macrocycle, therefore providing a better platform for biological studies.