Allostery in a monomeric protein: The case of human serum albumin

Human serum albumin (HSA), the most prominent protein in plasma, binds different classes of ligands at multiple sites. The globular domain structural organization of monomeric HSA is at the root of its allosteric properties which are reminiscent of those of multimeric proteins. Here, both functional and structural aspects of the allosteric modulation of heme and drug (e.g., warfarin and ibuprofen) binding to HSA and of the drug-dependent reactivity of HSA-heme are reviewed.