EAD OXIDE

J. Aranda, S. MacLeod, K. Renton, and N. Eade, Hepatic microsomal drug oxidation and electron transport in newborn infants, J. Pediatr, 85, 534 (1974). 

Each reaction of p oxidation is catalyzed by a different enzyme. Chemically, they re pretty much the same as the reverse of the individual reaction of fatty acid synthesis, with two exceptions (1) p oxidation uses EAD for the formation of the double bond at the C-2 position, and (2) the reactions occur with the fatty acid attached to CoA rather than to the pantetheine of a multienzyme complex. 

Eads reacts immediately, upon striking the fuel surface, to form two molecules of the product CO. It makes no significant difference whether the oxidant molecule is O2 or CO2 since, in either case, the product evolved is two molecules of CO. This rate of chemical adsorption is given by... 

Enzymatic cofactors, such as nicotinamide adenine dinucleotide (NADH), nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (EAD), flavin mononucleotide (EMN), and pyridoxal phosphate, are fluorescent and commonly found associated with various proteins where they are responsible for electron transport (see Fig. lb and Table 1). NADH and NADPH in the oxidized form are nonfluorescent, whereas conversely the flavins, FAD and EMN, are fluorescent only in the oxidized form. Both NADH and FAD fluorescence is quenched by the adenine found within their cofactor structures, whereas NADH-based cofactors generally remain fluorescent when interacting with protein structures. The fluorescence of these cofactors is often used to study the cofactors interaction with proteins as well as with related enzymatic kinetics (1, 9-12). However, their complex fluorescent characteristics have not led to widespread applications beyond their own intrinsic function. 

However, these experiments may not have established a mechanism for natural flavoprotein catalysis because the properhes of 5-deazaflavins resemble fhose of NAD+ more fhan of flavins. Their oxidation-reduction pofentials are low, they do not form sfable free radicals, and fheir reduced forms don f reacf readily with O2. Nevertheless, for an acyl-CoA dehydrogenase the rate of reaction of the deazaflavin is almost as fast as that of nafural EAD. Eor fhese enzymes a hydride ion fransfer from fhe P CH (reaction type D of Table 15-1) is made easy by removal of the a-H of the acyl-CoA to form an enolafe anion intermediate. 

The adsorption energies (Eads) of the various species in reactions (1) - (4) are essential information for understanding methanol oxidation. The results are collected in Table 6, together with available experimental data. Calculations were done for two types of sites, on-top (t) and threefold hollow (h). Excepting H and OH, the species treated prefer the on-top site in both pure and mixed clusters. 

Cu, Zn, Ge, Zr, and Rh have high D> c and E for water dissociation, and thus are unsuitable as secondary metals. The enhanced promoting effect of Re, W, or Mo toward H2O dissociation are due to strong M-OH adsorption, and large Eads(OH) does not promote oxidative removal of CO. For M = Re, the activation energy for the COads + OHads combination reaction is the highest of all, and thus the reaction becomes the rate-determining step in CO removal. 

Eight cycles of P-oxidation are required to convert one mole of stearic acid to nine moles of acetyl-GoA in the process eight moles of EAD are reduced to EADHg, and eight moles of NAD are reduced to NADH. 

The mechanism of poisoning automobile exhaust catalysts has been identified (71). Upon combustion in the cjdinder tetraethj ead (TEL) produces lead oxide which would accumulate in the combustion chamber except that ethylene dibromide [106-93 ] or other similar halide compounds were added to the gasoline along with TEL to form volatile lead halide compounds. Thus lead deposits in the cjdinder and on the spark plugs are minimized. Volatile lead halides (bromides or chlorides) would then exit the combustion chamber, and such volatile compounds would diffuse to catalyst surfaces by the same mechanisms as do carbon monoxide compounds. When adsorbed on the precious metal catalyst site, lead halide renders the catalytic site inactive. 

Lazarow and de Duve (1976) purified peroxisomes from rat liver and found that these were able to oxidize long chain acyl-CoA esters apparently via a (3-oxidation mechanism (Lazarow, 1978). This peroxisomal system differs distinctly from the well-characterized (3-oxidation system of mitochondria in a number of ways. The first dehydrogenation is carried out by an EAD dependent fatty acyl-CoA oxidase (Lazarow, 1978 Osumi and Hashimoto, 1978) and involves the reduction of O2 to H2O2. The enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase activities are carried out by a multifunctional protein (Osumi and Hashimoto, 1979, 1980). Also, the peroxisomal (3-ketothiolase has different chromatographic properties and chain length specificity from the mitochondrial enzyme (Krahling and Tolbert, 1981). 

The final stage of AD, known as LAD, carries Braak scores of IV-VI and a substantial presence of oxidative stress markers (Castegna et al. 2002a,b, 2003 Reed et al. 2008 Butterfield et al. 2013 Sultana et al. 2013). Clinically, this results in severe disability due to dementia and a great deal of required care. Similar to EAD, this dementia can be attributed at least in part due to the significant synapse loss and enlarged synapses found in LAD (Scheff et al. 1990). 

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