The effects of affinity and valency of an albumin-binding domain (ABD) on the half-life of a single-chain diabody-ABD fusion protein.

Fusion of small recombinant antibody fragments to an albumin-binding domain (ABD) from streptococcal protein G strongly extends their plasma half-life. This ABD binds with nanomolar affinity to human (HSA) and mouse serum albumin (MSA). It was speculated that an increase in albumin-binding affinity should lead to a further increase in half-life.