Catalase-peroxidase (KatG) is essential in Mycobacterium tuberculosis for oxidative stress management and activation of the antitubercular pro-drug isoniazid. The role of a unique distal side adduct found in KatG enzymes, involving linked side chains of residues Met255, Tyr229, and Trp107 (MYW), in the unusual catalase activity of KatG is addressed here and in our companion paper (Suarez, J., Ranguelova, K., Jarzecki, A. A., Manzerova, J., Krymov, V., Zhao, X., Yu, S., Metlitsky, L., Gerfen, G. J., and Magliozzo, R. S. (2009) J. Biol. Chem. 284, in press). The KatG[W107F] mutant exhibited severely reduced catalase activity yet normal peroxidase activity, and as isolated contains more abundant 6-coordinate heme in high spin and low spin forms compared with the wild-type enzyme. Most interestingly, oxyferrous heme is also found in the purified enzyme. Oxyferrous KatG[W107F] was prepared by photolysis in air of the carbonyl enzyme or was generated using hydrogen peroxide decayed with a t1/2 of 2 days compared with 6 min for wild-type protein. The stability of oxyenyzme was modestly enhanced in KatG[Y229F] but was not affected in KatG[M255A]. Optical stopped-flow experiments showed rapid formation of Compound I in KatG[W107F] and facile formation of oxyferrous heme in the presence of micromolar hydrogen peroxide. An analysis of the relationships between catalase activity, stability of oxyferrous enzyme, and a proposed MYW adduct radical is presented. The loss of catalase function is assigned to the loss of the MYW adduct radical and structural changes that lead to greatly enhanced stability of oxyenzyme, an intermediate of the catalase cycle of native enzyme.
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http://dx.doi.org/10.1074/jbc.M808107200 | DOI Listing |
Mar Biotechnol (NY)
January 2025
East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
As an abiotic stress factor, salinity significantly affects the physiological activities of crustaceans. In this study, transcriptome sequencing was used to evaluate the mechanism of ion transport and the physiological response of black tiger shrimp (Penaeus monodon) under low salt stress. Four hundred post larval (PL) stage P.
View Article and Find Full Text PDFNaunyn Schmiedebergs Arch Pharmacol
January 2025
Gastroenterology and Hepatology Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran.
Intestinal ischemia-reperfusion injury (IIR/I) significantly increases morbidity and mortality. This study examines the therapeutic effects of geraniol (GNL), which is noted for its anti-inflammatory and antioxidant properties, on intestinal I/R injury in rats. Forty-nine male Wistar-Albino rats were divided into seven groups.
View Article and Find Full Text PDFFree Radic Res
January 2025
Institute of Sport Sciences, University of Lausanne, Lausanne, Suisse.
Little is known regarding the effects high-intensity training performed in hypoxia on the oxidative stress and antioxidant systems. The aim of this study was to assess the potential effect of 4 weeks of repeated sprint training in hypoxia (RSH) on the redox balance. Forty male well-trained cyclists were matched into two different interventions (RSH, = 20) or in normoxia, RSN, = 20) and tested twice (before (Pre-) and after (Post-) a 4-week of training) for performance (repeated sprint ability (RSA) test), oxidative stress, and antioxidant status.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou 225001, China.
The intricacy, diversity, and heterogeneity of cancers make research focus on developing multimodal synergistic therapy strategies. Herein, an oxygen (O) self-feeding peroxisomal lactate oxidase (LOX)-based LOX-Ce6-Mn (LCM) was synthesized using a biomineralization approach, which was used for cascade chemodynamic therapy (CDT)/photodynamic therapy (PDT) combination therapies through dual depletion of lactate (Lac) and reactive oxygen species (ROS) generation. After endocytosis into tumor cells, the endogenous hydrogen peroxide (HO) can be converted to O by the catalase-like (CAT) activity of LCM, which can facilitate the catalytic reaction of LOX to consume more Lac and alleviate tumor hypoxia to enhance the generation of singlet oxygen (O) upon light irradiation.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Department of Cardiology, The First People's Hospital of Wenling, Wenling Hospital of Wenzhou Medical University, Wenling, Zhejiang, 317500, China.
Immobilizing enzymes onto solid supports having enhanced catalytic activity and resistance to harsh external conditions is considered as a promising and critical method of broadening enzymatic applications in biosensing, biocatalysis, and biomedical devices; however, it is considerably hampered by limited strategies. Here, a core-shell strategy involving a soft-core hexahistidine metal assembly (HmA) is innovatively developed and characterized with encapsulated enzymes (catalase (CAT), horseradish peroxidase, glucose oxidase (GOx), and cascade enzymes (CAT+GOx)) and hard porous shells (zeolitic imidazolate framework (ZIF), ZIF-8, ZIF-67, ZIF-90, calcium carbonate, and hydroxyapatite). The enzyme-friendly environment provided by the embedded HmA proves beneficial for enhanced catalytic activity, which is particularly effective in preserving fragile enzymes that will have been deactivated without the HmA core during the mineralization of porous shells.
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