Bcl-XL-binding helical peptides possessing<scp>d</scp>-Ala residues at their C-termini with the advantage of long-lasting intracellular stabilities

We attached D-Ala residues to cross-linked helical peptides based on the pro-apoptotic protein Bad at their C-termini. The D-Ala attachment had little influence on the secondary structures and binding abilities against Bcl-XL. The D-Ala attached helical peptides were much more stable in cells than original ones and efficiently induced apoptosis of the cells.