PMC3616395_01
a) HPLC results of the variant hemoglobin, which co-eluted with Hb A2 at a retention time of 3.56 minutes. b) Isoelectric focusing gel with variant hemoglobin in duplicate (arrows) with isoelectric point cathodal to Hb A and anodal to Hb F. c) DNA sequencing results of exon 2 of the alpha2 gene (forward strand). A TTC TCC substitution is present in codon 46, resulting in a Phe Ser amino acid substitution.
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F1
The heterozygous hemoglobin variant co-eluted with Hb A2 (retention time 3.56 minutes) and appeared slightly cathodal to Hb A and anodal to Hb F on isoelectric focusing using ResolveR system (Isolab Inc, Akron Ohio) (Figure 1 a&b). Gene sequencing at Mayo Clinic revealed a missense mutation in the alpha 2 gene, [HBA2:c.140T>C], resulting in a substitution of serine for phenylalanine at codon 46 (Figure 1 c).
Representation of the distal alpha-heme pocket of wild type hemoglobin with conserved amino acid residues. The rotation of HisE7 (His58) is thought to open a channel between heme and its ligand. PheCD4 (Phe46) may provide a gate to regulate the ease of this movement.
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F2