Dehydrogenases succinic

Complex II (Succinate Dehydrogenase Succinate Ubiquinone Oxidoreductase)... 

Succinate dehydrogenase (Succinate Q oxidore-ductase) Mitochondria and aerobic bacteria Succinate + Q — Fumarate -1- QH2 [PejSJ" [Pe3S,] [Pe,S,T" PAD I-2Cyt b -1-90 to -30 53,54... 

Dehydrogenases Glutathione reductase Acyl-CoA dehydrogenases Succinate dehydrogenase D-Lactate dehydrogenase... 

FIGURE 1. Respiratory chain the enzymes of the mitochondrial iimer membrane involved in oxidative phosphorylation. From complex I to V, they are NADH-dehydrogenase, succinate dehydrogenase, cytochrome bc complex, and cytochrome c oxidase. Protons are translocated across the membrane while electrons are transferred to Oj through the chain. The proton gradient is used by ATP synthase (complex V) to make ATP. (Reprinted with permission from Saraste, 1999, American Association for the Advancement of Science.)... 

The mitochondrial respiratory chain, which contains at least 13 Fe-S clusters (Figure 6), perhaps best illustrates the importance of Fe-S clusters in membrane-bound electron transport. Electrons enter via three principal pathways, from the oxidation of NADH to NAD+ (NADH-ubiquinone oxidoreductase or Complex I) and succinate to fumarate (succinate ubiquinone oxidoreductase or Complex II), and from the /3-oxidation of fatty acids via the electron transferring flavoprotein (ETF-ubiquinone oxidoreductase). All three pathways involve a complex Fe S flavoprotein dehydrogenase, that is, NADH dehydrogenase, succinate dehydrogenase, and ETF dehydrogenase, and in each case the Fe-S clusters mediate electron transfer from the flavin active site to the ubiquinone pool via protein-associated ubiquinone. 

Phosphatidic acid phosphatase Post proline cleaving enzyme Prostaglandin dehydrogenase Succinate dehydrogenase Sulfotransferase... 

FIGURE 13.8 Complexes of the respiratory chain. These include NADH dehydrogenase, succinate dehydrogenase (PDB code INEN), bci complex (PDB code 1PP9), cytochrome c oxidase (PDB code 1V54), and cytochrome c (PDB code IHRC). (From Hosier et at, 2006. Copyright 2006 with permission from Annual Reviews.)... 

Lewisite shares many biochemical mechanisms of injury with the other arsenical compounds. It inhibits many enzymes in particular, those with thiol groups, such as pyruvic oxidase, alcohol dehydrogenase, succinic oxidase, hexokinase, and succinic dehydrogenase. As is tme with mustard, the exact mechanism by which Lewisite damages cells has not been completely defined. Inactivation of carbohydrate metabolism, primarily because of inhibition of the pymvate dehydrogenase complex, is thought to be a key factor (Trammel, 1992). 

Some features of Fig. 2 warrant attention. It has been established from work with tubes that mitochondria form the major part of the fraction sedimenting in 1.4 M-sucrose and this is borne out in zonal studies by the high level of succinic dehydrogenase (succinate (acceptor) oxidoreductase, EC 1.3.99.1) (Table I). There was a... 

Their acute toxicity to mammals is low, but the two active substances may cause dermatitis. In rats fed daily on a diet containing quinomethionate a high cumulative toxicity was observed. A dietary level of 500 mg/kg for 90 days reduced body-weight, caused hypertrophy of the liver, and inhibited acetoacetate synthesis and the microsomal enzymes. It primarily inhibited the function of the HS-enzymes (pyruvate dehydrogenase, succinate dehydrogenase, malate dehydrogenase and a-ketoglutarate oxidase) (Carlson and DuBois, 1970). 

In addition to NADH dehydrogenase, succinic dehydrogenase and other flavopro-teins in the inner mitochondrial membrane also pass electrons to CoQ (see Fig. 21.5). Succinate dehydrogenase is part of the TCA cycle. ETF-CoQ oxidore-ductase accepts electrons from ETF (electron transferring flavoprotein), which acquires them from fatty acid oxidation and other pathways. Both of these flavo-proteins have Fe-S centers. a-Glycerophosphate dehydrogenase is a flavoprotein that is part of a shuttle for reoxidizing cytosolic NADH. 

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