Catalase expression

The physiology of catalase expression and its control in bacteria, yeast, and plants has been reviewed elsewhere (2, 26, 27). The following precis is presented so that a summary of physiological information relevant to the detailed biochemistry is readily available. 

The early work on catalase expression was carried out largely in E. coli and revealed two main response mechanisms. One or the other or both responses have been identified in most other bacteria expressing a catalase. The expected and most obvious response is to oxidative stress. Addition of hydrogen peroxide directly or of ascorbate, which... 

Regulation of catalase expression in eukaryotes takes place as part of a generalized response mechanism. In yeast, promoter elements of the peroxisomal catalase CTA-1 respond to glucose repression and activation by fatty acids as part of organelle synthesis. The cytosolic catalase CTT-1 responds as part of a generalized stress response to starvation, heat, high osmolarity, and H2O2, and there is even evidence of translational control mediated by heme availability 26). 

Nilakantan, V., Spear, B. T., and Glauert, H. P. (1998). Liver-specific catalase expression in transgenic mice inhibits NF-kappaB activation and DNA synthesis induced by the peroxisome proliferator cip-... 

The effectors of the mammalian host immune attack against filaria include reactive oxygen intermediates. Filarial nematodes express glutathione peroxidase, thioredoxin peroxidase and superoxide dismutase at their surface - enzymes believed to protect the nematode from this attack (Selkirk et al., 1998). A bacterial catalase gene has been identified that most probably derives from the endosymbiont genome (Henkle-Duhrsen et al., 1998) this enzyme may contribute with other enzymes to the protection of both Wolbachia and its nematode host from oxygen radicals. 

The reaction stoichiometry is given in Eq. (17). The reaction in Eq. (17) follows first-order kinetics in 1 in the absence of an electron donor. Thus, the rate expression (Eq. (18)) holds for the catalase-like activity, which is identical to Eq. (15). 

The molecular masses of heme catalases are usually significantly higher as compared with peroxidases. If expressed in Lg-1s-1, rate constants for the Fem-TAML activators when compared with catalase from beef liver, which has a molecular weight 250,000 gmol-1 (Table IV, entry 13) (89), look very impressive, viz. 17 L g 1 s-1 for 11 vs. 22 L g 1 s 1 for the enzyme. Nevertheless, the catalase-like activity of the Fem-TAML activators can be suppressed by the addition of electron donors -it is negligible in the presence of the substrates tested in this work. In Nature, catalases display only minor peroxidase-like activity (79) because electron donors bulkier than H202 cannot access the deeply buried active sites of these massive enzymes (90). The comparatively unprotected Fem-TAML active sites are directly exposed to electron donors such that the overall behavior is determined by the inherent relative reactivity of the substrates. 

Numerous studies demonstrated that lipid peroxidation significantly decreased in cancer cells and tissues (Ref. [176] and references therein). It has been proposed that this can be a consequence of a decrease in the content of highly unsaturated fatty acids, the concentration of cytochrome p-450, and the contents of NADPH, SOD, and catalase in tumors. Cheeseman et al. [176] suggested that the reduction of lipid peroxidation in tumors may depend on both the expression of malignant transformation and cell division. It should be mentioned that Boyd and McGuire [177] demonstrated that there is a correlation between lipid peroxidation and breast cancer risk in premenopausal women. 

The BEAS-2B cell line has been described previously as retaining the expression of most of the phase II enzymes (i.e., epoxide hydrolase, GST pi, GSH peroxidase and catalase) [121], However, when Kuzuya and co-workers quantitatively compared UGT levels amongst NHBE, Calu-3 and BEAS-2B cells, the Calu-3 cell line showed expression levels most comparable to NHBE, while results from BEAS-2B cells were significantly different from others (Table 10.2) [116],... 

Expression of the multiple catalases in plants (e.g., three in maize and four in mustard) are developmentally controlled, giving rise to complex response patterns. The picture is further complicated by overlapping responses to environmental stresses such as pathogenesis, radiation, hormones, temperature extremes, oxygen extremes, and H2O2 27). 

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