Superoxide utilizing enzyme

Hayaishi, Osamu, Takikawa, Osamu, and Yoshida, Ryotaro, Indoleamine 2,3-Dioxygenase, Properties and Functions of a Superoxide Utilizing Enzyme 38 75... 

Indoleamine 2,3-Dioxygenase Properties and Functions of a Superoxide Utilizing Enzyme... 

Dioxygenase, Properties and Functions (fa Superoxide Utilizing Enzyme Heintz, Robert A., see Dunbar, Kim R. 

These membranes are devoid of cytochrome oxidase, and the alternative 02-utilizing enzymes within them generate superoxide as a primary product. The question arises therefore as to whether superoxide formation could be linked to free energy conservation. A plausible mechanism can be suggested. 

The scientific programme comprised four main themes photo-oxygen evolution superoxides, intermediates between oxygen and water biological oxygen transport and oxygen-utilizing enzymes. 

Aerobic aerobic microorganisms utilize oxygen as a terminal electron acceptor and possess superoxide dismutase or catalase enzymes which are capable of degrading peroxide radicals. 

Riley, D.P. Rational design of synthetic enzymes and their potential utility as human pharmaceuticals development of manganese(II)-based superoxide dismutase mimics. Adv. Supramol. Chem. 2000, 6, 217-244. 

Oxygen-utilizing organisms have generally evolved specific enzyme-mediated systems that serve to protect the cell from such reactive species. These enzymes include superoxide dismutase (SOD) and catalase or glutathione peroxidase (GSH-px), which catalyse the following reactions ... 

Molecular oxygen usually reacts rapidly with only those organic substrates, such as dihydroflavins, that are able to form stable free radicals. However, the endiolate anion of Eq. 13-50 may be able to donate a single electron to 02 to form a superoxide-organic radical pair prior to formation of the peroxide (see also Eq. 15-30). Similar oxygenase side reactions have been observed for a variety of other enzymes that utilize carbanion mechanisms.283 The reaction of rubisco with 02 is of both theoretical and practical interest, the latter because of its significance in lowering the yield in photosynthesis (Chapter 23). 

Partially reduced dioxygen species are utilized in the reactions of various enzymes. Thus, monooxygenases may use bound superoxide, while cytochrome P-450 utilizes bound peroxide in its hydroxylation reactions.1231... 

The existence of proteins such as Superoxide Dismutase and Catalase in aerobes often is cited in support of the conclusion that 02 - and HOOH are biological toxins. The present understanding of the biological utilization of hydrogen peroxide includes enzyme-facilitated processes that involve its disproportionation, the dehydrogenation of organic molecules, and the production of hypochlorous acid in neutrophils (equations 23-25). 

---