Haemoglobin binding with haptoglobin. Localization of the haptoglobin-binding site on the α-chain of human haemoglobin

Abstract

A synthetic approach was employed to identify the haptoglobin-binding site on the α-chain of human haemoglobin. This approach consists of the synthesis of a series of consecutive overlapping peptides that, together, systematically represent the entire protein chain. Fourteen peptides were synthesized (α1-15, α11-25, α21-35, α31-45, α41-55, α51-65, α61-75, α71-85, α81-95, α91-105, α101-115, α111-125, α121-135 and α131-141), and their ability to bind human haptoglobin was studied. Only peptide α121-135 bound haptoglobin significantly. On this basis we conclude that the haptoglobin-binding site on the α-chain of haemoglobin resides within, but does not necessarily encompass all of, the region α121-135.