Patent ID: 7666979

Claim:
A method for preparing a heterodimer comprising the formula: A-B-C-D-E-B′-F wherein A is a first peptide, B is a first branching group, C is an optional first spacer, D is a linker comprising glutaric acid, E is an optional second spacer which may be the same as or different from said first spacer C, B′ is an optional second branching group which may be the same as or different from said first branching group B, and F is a second peptide which is different from said first peptide A; said method comprising the steps of: (a) covalently bonding A and B and optionally C; (b) activating the linker D; (c) reacting an excess of the activated linker D with the product of (a); (d) removing any excess activated linker D; (e) covalently bonding F optionally conjugated to B′ and/or E.