Peroxidase, Catalase

Bertrand T, NAJ Eady, IN Jones, Jesmin, JM Nagy, B Jamart-Gregoire, EL Raven, KA Brown (2004) Crystal structure of Mycobacterium tuberculosis catalase-peroxidase. J Biol Chem 279 38991-38999. 

Zhao X, S Girotto, S Yu, RS Magliozzo (2004) Evidence for radical formation at Tyr-353 in Mycobacterium tuberculosis catalase-peroxidase (KatG) J Biol Chem 279 7606-7612. 

Enzyme-mediated action, by sulfhydryl and phenylalanine-lyase (PAL) enzymes as well as by other enzymes such as cellulase, catalase, peroxidase, phosphorylase and pectolytic enzymes ... 

The prodrug isoniazid (34) targets M. tuberculosis InhA [3] after activation by a mycobacterial catalase-peroxidase by reacting irreversibly with the cofactor nicotinamide adenine dinucleotide (NAD). This covalent adduct... 

Direct InhA inhibitors have also been sought to avoid isoniazid resistance mediated by catalase-peroxidase mutation. Lipophilic analogs of triclosan such as 36 show a nanomolar K on the enzyme with an MIC of 1-2 pg/mL on isoniazid-resistant strains [56]. Structure-based optimization of two separate HTS leads afforded 37 and 38, both submicromolar inhibitors of InhA but devoid of any significant antibacterial activity [57,58],... 

Z. Zhang, S. Chouchane, R.S. Magliozzo, and J.F. Rusling, Direct voltammetry and catalysis with Mycobacterium tuberculosis catalase-peroxidase, peroxidases, and catalase in lipid films. Anal. Chem. 74,163-170 (2002). 

Activators of Hydrogen Peroxide, Functional Catalase-Peroxidase Replicas 494... 

General descriptors may be related to the metabolism responses in the biofilm. Biofilm algae have several mechanisms to counterbalance the damage caused by the toxicants. Environmental stress produces oxidative damage in the cells, which can be tracked down by means of the analysis of many enzymes (superoxide dismutase, catalase, peroxidase, etc.) that function as effective quenchers of reactive oxygen species (ROS). 

Manganese is the cofactor for catalases, peroxidases and superoxide dismutases, which are all involved in the detoxification of reactive oxygen species (SOD). We consider here the widely distributed Mn SOD, and then briefly describe the dinuclear Mn catalases. 

In addition to binding to cytochrome c oxidase, cyanide inhibits catalase, peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, and succinic dehydrogenase activities. These reactions may make contributions to the signs of cyanide toxicity (Ardelt et al. 1989 Rieders 1971). Signs of cyanide intoxication include an initial hyperpnea followed by dyspnea and then convulsions (Rieders 1971 Way 1984). These effects are due to initial stimulation of carotid and aortic bodies and effects on the central nervous system. Death is caused by respiratory collapse resulting from central nervous system toxicity. 

Zou P-J, Borovok I, Ortiz de Orud Lucana D, et al. 1999. The mycelium-associated Streptomyces reticuli catalase-peroxidase, its gene and regulation by FurS. Microbiology 145 549-59. 

Todd, G. W. Effect of low concentrations of ozone on the enzymes catalase, peroxidase, papain and urease. Physiol. Plant. 11 457-463, 1958. 

Generally, the peroxidatic reaction of true catalases is weak in comparison to actual peroxidases, but can be an important reaction in the class known as catalase-peroxidases (Section II,B). 

The diversity among catalases, evident in the variety of subunit sizes, the number of quaternary structures, the different heme prosthetic groups, and the variety of sequence groups, enables them to be organized in four main groups the classic monofunctional enzymes (type A), the catalase-peroxidases (type B), the nonheme catalases (type C), and miscellaneous proteins with minor catalatic activities (type D). 

The next largest group of catalases are the catalase-peroxidases, so named because they exhibit a significant peroxidatic activity in addition to the catalatic activity. They have been characterized in both fungi and bacteria and resemble certain (type I) plant and fungal peroxidases... 

A phylogenetic analysis of the catalase-peroxidase sequences (2) now extended to 20 available sequences, does not reveal any major subgroupings comparable to those in the catalase family. Whether this is because of the small number of sequences or because of the homogeneity of the enzymes will become evident as further sequences come available. As a result we will, for the time being, refer to the catalase-peroxidases as a single group of enzymes. 

The more complex scheme required if a true is involved is shown in Fig. 2B. There are two possible steps that could provide limiting unimolecular processes, governed by and k, the steps involved in formation of compound I and the decay of the ternary complex, respectively. Nicholls and Schonbaum (22) gave reasons the latter is the preferred limiting step for mammalian catalase. These reasons have not changed much over the past 35 years. But the increased number of catalases examined, especially the catalase-peroxidases, makes reevaluation appropriate (see below). 

Several catalases, including the type B catalase-peroxidases, seem to show true substrate saturation at much lower levels of peroxide than originally observed for the mammalian enzyme (in the range of a few millimolar). This means that the limiting maximal turnover is less and the lifetime of the putative Michaelis-Menten intermediate (with the redox equivalent of two molecules of peroxide bound) is much longer. The extended scheme for catalase in Fig. 2B shows that relationships between free enzyme and compound I, and the presumed rate-limiting ternary complex with least stability or fastest decay in eukaryotic enzymes of type A and greatest stability or slowest decay in prokaryotic type B enzymes. 

There are also substantial differences between classical type A enzymes and the type B catalase-peroxidases. The latter enz5mies, although they show peroxidase activity toward donors of type D2, are inactive or only weakly active toward D3 donors such as ethanol. 

Both classical type A enzymes (clade III) and the heme d family (clade II) show a comparatively high sensitivity to azide inhibition and are reduced to ferrous forms in the presence of peroxide and azide (47). In contrast, the catalase-peroxidase (type B) enzymes (see below) are only weakly azide-sensitive. 

Fig. 7. Catalatic and peroxidatic reactions of type B enzymes. This represents a modification of the schemes of Figs. 2 and 5A and is proposed to account for the characteristic features of catalase-peroxidases. Compound I is drawn as Fe +=0 and can represent either a -rr-cation radical or alternative radical structure. The precise nature remains undefined (see Section IV,F).

---