Fig. 4. Peroxidase activity of designed β-sheet peptides. (A) Time course of ABTS oxidation at 700 nm for four stranded peptide–heme complexes at 4 mM H₂O₂ concentration. (B) Absorbance of ABTS oxidation at 700 nm versus time for six stranded peptide–heme complexes at 4 mM H₂O₂ concentration. (C) Steady-state kinetics of ABTS oxidation as a function of hydrogen peroxide concentration for peptides 2, 4, 5 and 7. (D) Steady-state kinetics of ABTS oxidation as a function of hydrogen peroxide concentration for peptides 8, 9 and 10. In all cases, the final heme, peptide and ABTS concentration were 0.5 μM, 4 μM and 2.5 mM respectively in sodium phosphate buffer, pH 7.2 containing 2 mM DPC. The data was fitted to a Michaelis–Menten equation to derive catalytic parameters (Table 1).