Fetal hemoglobin (HbF) is a tetramer composed of two [alpha]- and two [gamma]-chains. The [gamma]-chains differ from the [beta]-chains of HbA at 39 residues, but a Cys residue at position 93, which is the residue that becomes S-nitrosated in HbA, is conserved.  As Cu,Zn-superoxide dismutase (CuZnSOD) has been suggested to participate in Hb-SNO formation, levels of the enzyme were measured in adult and newborn red blood cell (RBC) lysates by means of the pyrogallol assay. CuZnSOD levels were found to be higher in the newborn than in the adult lysates. Recently, it has been shown that HbF can be S-nitrosated in both its deoxy and oxy forms, but only oxyHbA is S-nitrosated. Also, our collaborators have shown an inverse correlation between the amount of Hb-SNO and HbF measured in chord blood samples collected from newborns, while no difference was detected in nitrosylHb (HbFe II NO) levels. (Abstract shortened by UMI.)