Ordered heme binding ensures the assembly of fully functional hemoglobin: a hypothesis.

The exact mechanism by which four Fe-Protoporphyrin-IX (heme) moieties and four nascent globin chains combine to form human hemoglobin (alpha(2)beta(2)) remains a mystery. Recent Soret spectral static and kinetic studies of the incorporation of CN-Hemin derivatives into an array of human globin species have provided in vitro evidence of an ordered assembly pathway, through an alphaheme-betaglobin intermediate, that ensures correct formation of active hemoglobin tetramers.