Effect of Distal Cavity Mutations on the Formation of Compound I in Catalase-Peroxidases

• DOI: 10.1074/jbc.m002371200
• Publication Date: 2002-07-26T15:04:49Z
• Authors: Günther Regelsberger; Christa Jakopitsch; Florian Rüker; Daniel Krois; Günter A. Peschek; Christian Obinger
• Keywords: Cytochrome c peroxidase; Peroxide

Catalase-peroxidases have a predominant catalase activity but differ from monofunctional catalases in exhibiting substantial peroxidase and having different residues the heme cavity. We present kinetic study of formation key intermediate compound I by probing role conserved distal amino acid triad Arg-Trp-His recombinant catalase-peroxidase its reaction with hydrogen peroxide, peroxoacetic acid, <i>m</i>-chloroperbenzoic acid. Both wild-type enzyme six mutants (R119A, R119N, W122F, W122A, H123Q, H123E) been investigated steady-state stopped-flow spectroscopy. The turnover number R119A is 14.6%, R119N 0.5%, H123E 0.03%, H123Q 0.02% activity. Interestingly, W122F W122A completely lost their retained Bimolecular rate constants determined. Trp-122 for first time made it possible to follow transition ferric peroxide spectroscopically underlining important results demonstrate that His-Arg pair catalase-peroxidases heterolytic cleavage (<i>i.e.</i> formation), whereas tryptophan essential reduction peroxide.