Structural and Functional Information of Human Hemoglobin Subunit μ.

Abstract

The human hemoglobin subunit μ (Hb-μ) has been identified as a potential biomarker for α-thalassemia. However, little structural and functional information is available for this subunit. Here, we have overexpressed and purified a double mutant of C49S/C104S Hb-μ and solved its X-ray crystal structure. It adopts a typical protein fold of the globins, similar to that of the α-subunit. The structure also reveals that the protein undergoes self-oxidation of Met62 in the heme distal site, producing the form of sulfoxide (Met-SO). The property and function have also been studied by spectroscopy, which shows that the protein has considerable peroxidase activity due to the presence of a catalytic His-Arg pair in the heme distal site. The structure-function relationship of Hb-μ obtained in this study may provide useful insights into Hb-related diseases.