Tryptic peptide maps of the α-chains. The α-chains of HbA (A) and E6V(β)/D85K(α) (B) were isolated, carboxymethylated, and digested with trypsin as described in the text. The resulting peptides were separated on a Vydac 400VHP575 strong cation exchange column by NaCl gradient (0 to 100 mmol/L) in 20 mmol/L Na-acetate/10% acetonitrile buffer (pH 5.2). The arrow shows the mutant pentapeptide.