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 ...

This study focuses on the mechanisms for hydrogen peroxide detoxification in Synechococcus sp. strain PCC 7942. To gain better understanding of the role of different routes of hydrogen peroxide detoxification, we inactivated TplA (thioredoxin-peroxidase-like), which we recently identified. In addition, we inactivated the gene encoding catalase-peroxidase and examined the ability to detoxify H(2...

Proteins are subject to continuous quality control for optimal proteostasis. The knowledge of peroxisome quality control systems is still in its infancy. Here we show that peroxisomes contain a member of the Lon family of proteases (Pln). We show that Pln is a heptameric protein and acts as an ATP-fueled protease and chaperone. Hence, Pln is the first chaperone identified in fungal peroxisomes....

The catalase within normal, intact human erythrocytes was completely inactivated with amino triazole. The rate of 14CO2 evolution, when the cells were subsequently incubated with 14C-labeled glucose, provided a measure of the rate at which NADPH was being oxidized by the glutathione peroxidase/reductase system for the disposal of H2O2. This rate was determined in control cells and in catalase-i...

The physical properties and activities of the purified catalase-peroxidase hydroperoxidase I (HPI) of Escherichia coli (EcHPI) and HPI with a carboxyl-terminal extension of Mycobacterium tuberculosis (MtHPI-e) are compared to those of commercial preparations of horseradish peroxidase (HRP). The catalase-peroxidase proteins had similar absorption spectra and differed primarily in that MtHPI-e ha...

The activities of catalase, peroxidase, and polyphenoloxidase were studied in attached and detached rice (Oryza sativa L. cv. Ratna) leaves. Catalase activity decreased while peroxidase and polyphenoloxidase activities increased during senescence of both attached and detached rice leaves. Kinetic (5 mum) and benzimidazole (1 mm), which are known to delay the senescence of detached rice leaves, ...

the aims of this study were to assess the effects of drought stress on peroxidase (pod), superoxide dismutase (sod) and catalase (cat) activities as well as free proline content and growth parameters of pistacia khinjuk seedlings under drought stress. therefore, the one-year seedlings of pistacia khinjuk subjected to water stress (25%, 50%, 75%, and 100% field capacity) for 8 months in greenhou...

the role of zinc (zn) in enhancing defense capacity of several plants against salinity has been demonstrated but there is limited information on the impact of zn nutrition on alleviating salinity-induced oxidative damage in olive. one-year-old seedlings of two varieties of olive (olea europaea l. cvs. frontoio and conservolea) supplied with three zn levels (0, 1 and 5 mm in the form of znso4.7h...

We examined 40 strains of Legionella for reduced-oxygen scavenging enzymes. Using a simple reaction chamber with a Swinney filter for the Beers and Sizer assay, we determined the catalase activity of live cells grown on buffered charcoal-yeast extract agar. For 29 strains of Legionella pneumophila, the apparent first-order rate constants for catalase ranged from 0.000 to 0.005. Similarly, low v...