Binding equilibria and catalase-like reactivity of deuteroferrihaem–poly-L-lysine complexes

Abstract

At pH 10.5, 25 °C, and ionic strength 0.1 mol dm^–3, deuteroferrihaem binds to poly-L-lysine as a monomeric haem species with a single axial lysine ligand. The observed rate constant for catalytic decomposition of H₂O₂ by deuteroferrihaem increases initially with increasing [poly-L-lysine] but then falls rapidly at higher [poly-L-lysine]. The results imply that the catalytic rate constant for poly-L-lysine bound deuteroferrihaem monomer is closely similar to that of free deuteroferrihaem monomer at low [poly-L-lysine] but decreases sharply (by almost 10³ fold) at higher [poly-L-lysine].