Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in facilitating the reaction between the peroxidase and hydrogen peroxide with the formation of Compound I. In ...

Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in facilitating the reaction between the peroxidase and hydrogen peroxide with the formation of Compound I. In ...

Hydrogen peroxide (H2O2), an important relatively stable non-radical reactive oxygen species (ROS) is produced by normal aerobic metabolism in plants. At low concentrations, H2O2 acts as a signal molecule involved in the regulation of specific biological/physiological processes (photosynthetic functions, cell cycle, growth and development, plant responses to biotic and abiotic stresses). Oxidat...

Through genetic engineering technology, catalase (CAT) and superoxide dismutase (SOD) have been separately fused to an elastin-like polypeptide (ELP). Thus, the enzymes can be purified through phase transition. Hexadecylamine-modified poly(aspartic acid) (HPASP) is able to self-assemble, forming soft microparticles. The HPASP microparticles were used to co-immobilize SOD-ELP and CAT-ELP through...

SOME RECENT ARTICLES IN The FASEB Journal have dealt with an important topic, that of free radicals and their effects on biological structures (1-3). In these and many other studies of high scientific level there is the tacit or explicit assumption that mitochondria are a primary source of free oxygen radicals, such as superoxide. We would like to clarify this issue, referring to the original (...

Chloroperoxidase catalyzes the dismutation of chlorite-forming chloride, chlorine dioxide, chlorate, and oxygen as products. The yields of chlorine dioxide are variable because chloroperoxidase also catalyzes the decomposition of this compound and, in addition, moderate concentrations of chlorine dioxide inactivate the enzyme. Chloride, chlorate, and oxygen are the products of the decomposition...

7,8-Dihydroneopterin and neopterin are secreted by human and primate macrophages after activation by interferon-gamma in a ratio of 2:1. 7,8-Dihydroneopterin is known to suppress radical-mediated processes, but it is also able in the presence of iron ions to generate superoxide radical anion and hydroxyl radicals from molecular oxygen. Effects of 7,8-dihydroneopterin were investigated on (met)m...

Highly purified iron superoxide dismutase was obtained from Escherichia coli B using a modification of the procedure of Yost and Jridovich (Yost, F. J., Jr., and Fridovich, I. (1973) J. Biol. Chem. 248, 4905-4908). The protein contained 1.8 +/- 0.2 atoms of iron per 38,700 g of protein. We have found that cyanide does not bind to the Fe3+ ion of iron dismutase but fluoride and azide have modera...

O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH.. SODs inhibit such HO. production by scavengingO2-, but Cu, ZnSODs, by virtue of a nonspecific peroxidase activity, may peroxidize spin trapping agents and thus give the appearance of catalyzing OH. production from H2O2. There is a glycosylate...

Polymorphonuclear leukocytes and other inflammatory cells release superoxide anion and additional oxidant species following stimulation. Corneal endothelial cells were exposed to a flux of chemically generated superoxide anion (oxygen-free radical) produced by the combination of 1 mM hypoxanthine and 0.06 U/ml xanthine oxidase. Exposure of endothelial cells to the combination of hypoxanthine an...