The claim that succinate and malate can directly stimulate the activity of the alternative oxidase in plant mitochondria (A.M. Wagner, C.W.M. van den Bergen, H. Wincencjusz [1995] Plant Physiol 108: 1035-1042) was reinvestigated using sweet potato (Ipomoea batatas L.) mitochondria. In whole mitochondria, succinate (in the presence of malonate) and both L- and D-malate stimulated respiration via...

It was found that Acidithiobacillus thiooxidans has sulfite:ubiquinone oxidoreductase and ubiquinol oxidase activities in the cells. Ubiquinol oxidase was purified from plasma membranes of strain NB1-3 in a nearly homogeneous state. A purified enzyme showed absorption peaks at 419 and 595 nm in the oxidized form and at 442 and 605 nm in the reduced form. Pyridine ferrohaemochrome prepared from ...

Cytochrome c oxidase from bakers’ yeast contains three mitochondrially made subunits (I to III) which are relatively hydrophobic and four cytoplasmically made subunits (IV to VII) which are relatively hydrophilic (Mason. T. L., Poyton, R. O., Wharton, D. C., and Schatz, G. (1973) J. Biol. Chem. 248, 1346-1354 and Poyton, R. O., and Schatz, G. (1975) J. Biol. Chem. 250, 752-761. In order to expl...

The enzymatic properties and cellular localization of a-hydroxy acid oxidase have been studied in renal tissue of the rat. The enzyme was most active in the presence of D, La-hydroxy valeric acid and D, La-hydroxy butyric acid and was inactive in the presence of glycolic acid and D-alanine. It appeared to have no cofactor requirement. When subjected to electrophoresis in acrylamide gels, follow...

The renewed interest in exploring various natural habitat/environments for discovering novel microbial sources as stable cholesterol oxidase producers is on the incline due to its broad-range of clinical and industrial applications. A search was conducted to isolate cholesterol oxidase producing bacteria from samples collected from different environments. A total of 98 bacterial isolates capabl...

In Escherichia coli, quinolinic acid, a precursor of NAD+, is synthesized from L-aspartate and dihydroxyacetone phosphate. This synthesis requires two enzymes, a FAD-containing "B protein" and an "A protein." The B protein has been purified 500-fold from E. coli cells. The enzyme behaves as an L-aspartate oxidase. In the absence of A protein, it converts L-aspartate to oxaloacetate. To our know...

An aldehyde oxidase, which oxidizes various aliphatic and aromatic aldehydes using O(2) as an electron acceptor, was purified from the cell-free extracts of Pseudomonas sp. KY 4690, a soil isolate, to an electrophoretically homogeneous state. The purified enzyme had a molecular mass of 132 kDa and consisted of three non-identical subunits with molecular masses of 88, 39, and 18 kDa. The absorpt...

Yang B, Rizzo V. TNFpotentiates protein-tyrosine nitration through activation of NADPH oxidase and eNOS localized in membrane rafts and caveolae of bovine aortic endothelial cells. Am J Physiol Heart Circ Physiol 292: H954–H962, 2007. First published October 6, 2006; doi:10.1152/ajpheart.00758.2006.—A major source of reactive oxygen species (ROS) in endothelial cells is the NADPH oxidase enzyme...

polyphenol oxidase (ppo), also known as tyrosinase (ec 1.14.18.1), is a copper-containing enzyme widely distributed in microorganisms, animals, and plants. this enzyme is responsible not only for browning in plants but also for melanization in animals. thus, tyrosinase inhibitors have a huge impact on industry and the economy. in the current study, we first purified the enzyme, then evaluated i...