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Gewählte Publikation:

Regelsberger, G; Jakopitsch, C; Furtmüller, PG; Rueker, F; Switala, J; Loewen, PC; Obinger, C.
(2001): The role of distal tryptophan in the bifunctional activity of catalase-peroxidases.
Biochem Soc Trans. 2001; 29(Pt 2):99-105

Catalase-peroxidases are bifunctional peroxidases exhibiting an overwhelming catalase activity and a substantial peroxidase activity. Here we present a kinetic study of the formation and reduction of the key intermediate compound I by probing the role of the conserved tryptophan at the distal haem cavity site. Two wild-type proteins and three mutants of Synechocystis catalase-peroxidase (W122A and W122F) and Escherichia coli catalase-peroxidase (W105F) have been investigated by steady-state and stopped-flow spectroscopy. W122F and W122A completely lost their catalase activity whereas in W105F the catalase activity was reduced by a factor of about 5000. However, the mutations did not influence both formation of compound I and its reduction by peroxidase substrates. It was demonstrated unequivocally that the rate of compound I reduction by pyrogallol or o-dianisidine sometimes even exceeded that of the wild-type enzyme. This study demonstrates that the indole ring of distal Trp in catalase-peroxidases is essential for the two-electron reduction of compound I by hydrogen peroxide but not for compound I formation or for peroxidase reactivity (i.e. the one-electron reduction of compound I).
Autor*innen der BOKU Wien:
Furtmüller Paul Georg
Jakopitsch Christa
Obinger Christian
Rüker Florian
Find related publications in this database (using NML MeSH Indexing)
Bacterial Proteins -
Binding Sites -
Catalysis -
Cyanobacteria - enzymology
Cytochrome-c Peroxidase - chemistry
Escherichia coli - enzymology
Heme - metabolism
Hydrogen Peroxide - metabolism
Kinetics - metabolism
Multienzyme Complexes - chemistry
Mutation - genetics
Oxidation-Reduction - genetics
Peroxidases - chemistry
Protein Binding - chemistry
Spectrophotometry - chemistry
Tryptophan - genetics
Yeasts - enzymology

Find related publications in this database (Keywords)
catalase activity
Escherichia coli
synechocystis PCC 6803

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