where: X is NCO???(CH2)2???NH???Y and Y is a suitable protecting group, such as a t-butyloxycarbonyl (Boc) protecting group; A* is a suitable functional group, such as N-oxy succinimide, used to conjugate C1 of the linker to the ??-amino group of the C-terminal lysine residue of the first peptide monomer; and B* is a suitable functional group, such as N-oxy succinimide, used to conjugate C2 of the