Figure 1).
Schematic structural illustration of the different haptoglobin (Hp) phenotypes. The α1 chain forms disulphide bonds with one alpha-chain and one beta-chain. Thus, in subjects with Hp 1-1, a linear 86 kDa (α1β)2 homodimer is found. The α2 chain can bind one beta-chain, and either one α1 or two α2 chains. Therefore, Hp 2-2 is expressed as cyclic (α2β)n multimers with a molecular weight ranging between 170 and 900 kDa. Individuals with Hp 2-1 have (α1β)2 homodimers and linear (α2β)n multimers with a molecular weight of 86 to 300 kDa (16)