2-Oxoglutarate dehydrogenase complex

As with some other enzymes involved in the generation of ATP in the mitochondria (e.g. oxoglutarate dehydrogenase), aconitase possesses an iron-sulphur complex in its... 

Now this reaction is effectively a repeat of the pyruvate acetyl-CoA oxidative decarboxylation we saw at the beginning of the Krebs cycle. It similarly requires thiamine diphosphate, lipoic acid, coenzyme A and NAD+. A further feature in common with that reaction is that 2-oxoglutarate dehydrogenase is also an enzyme complex comprised of three separate enzyme activities. 2-Oxoglutarate is thus transformed into succinyl-CoA, with the loss of... 

The intermediary metabolism has multienzyme complexes which, in a complex reaction, catalyze the oxidative decarboxylation of 2-oxoacids and the transfer to coenzyme A of the acyl residue produced. NAD" acts as the electron acceptor. In addition, thiamine diphosphate, lipoamide, and FAD are also involved in the reaction. The oxoacid dehydrogenases include a) the pyruvate dehydrogenase complex (PDH, pyruvate acetyl CoA), b) the 2-oxoglutarate dehydrogenase complex of the tricarboxylic acid cycle (ODH, 2-oxoglutarate succinyl CoA), and c) the branched chain dehydrogenase complex, which is involved in the catabolism of valine, leucine, and isoleucine (see p. 414). 

The next step, the formation of succinyl CoA, also involves one oxidation and one decarboxylation. it is catalyzed by 2-oxoglutarate dehydrogenase, a multienzyme complex closely resembling the PDH complex (see... 

GA Rutter, RM Denton. The binding of Ca2+ ions to pig heart NAD+-isocitrate dehydrogenase and the 2-oxoglutarate dehydrogenase complex. Biochem J 263 453-462, 1989. 

Step 4 is the production of succinyl-CoA from 2-oxoglutarate and coenzyme A (CoASH), catalyzed by the 2-oxoglutarate dehydrogenase complex (which is often called a-ketoglutarate... 

The third control step in the citric acid cycle is catalyzed by 2-oxoglutarate dehydrogenase. This multienzyme complex is subject to product inhibition by both NADH and succinyl-CoA. Yet again,... 

The studies of Peters in the 1920s and 1930s (Peters, 1963) established the coenzyme role of thiamin in the oxidative decarboxylation of pyruvate. Thiamin diphosphate is the coenzyme for three multienzyme complexes in mammalian mitochondria that are involved in the oxidative decarboxylation of oxo-acids pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase in central... 

Branched-Chain Oxo-acid Decarboxylase and Maple Syrup Urine Disease The third oxo-add dehydrogenase catalyzes the oxidative decarboxylation of the branched-chain oxo-acids that arise from the transamination of the branched-chain amino acids, leucine, isoleuctne, emd vtdine. It has a similEU subunit composition to pyruvate and 2-oxoglutarate dehydrogenases, and the E3 subunit (dihydrolipoyl dehydrogenase) is the stune protein as in the other two multienzyme complexes. Genetic lack of this enzyme causes maple syrup urine disease, so-called because the bremched-chain oxo-acids that are excreted in the urine have a smell reminiscent of maple syrup. 

In aerobic environments, eukaryotes and many eubacteria oxidatively decarboxylate the 2-oxoacids via pyruvate and 2-oxoglutarate dehydrogenase complexes [36]. For comparison with the archaebacterial oxidoreductases, the catalytic mechanism of these complexes is also shown in Fig. 4. Three enzymic activities are involved, catalysed by three distinct enzymes a 2-oxoacid decarboxylase (El), a dihydrolipoyl acyltransferase (E2) and dihydrolipoamide dehydrogenase (E3). Multiple copies of these three enzymes are found in each complex molecule, resulting in relative molecular masses in excess of 2x10 ... 

Important sites of inhibition are the pyruvate dehydrogenase complex, which converts pyruvate into acetyl-CoA isocitrate dehydrogenase, which converts isocitrate into 2-oxoglutarate and 2-oxoglutarate dehydrogenase. The enzyme citrate synthase, which catalyzes the first reaction of the cycle, is also inhibited by ATP. ... 

OptCircuit framework 101 oral immunization 619 organic acids 156 OROPON 15,278 2-oxoglutarate dehydrogenase complex (2-OGDH) 596 oxygenic photosynthesis 582 -oxidation 650... 

The genes encoding two enzymes from the TCA cycle the 2-oxoglutarate dehydrogenase complex and malate dehydrogenase for the TCA cycle are reported to be... 

Fig. 2. Mechanism of the oxidative decarboxylation of 2-oxoglutarate by the 2- oxoglutarate dehydrogenase complex EC 1.2.4.2). Enzyme, = 2-oxoglutarate decarboxylase. Enzym = lipoyl-redurtase-transacetylase (lipoyl reductase-t-transsuccinylase). Enzymej = dihydrolipoyl dehydrogenase, tpp-thiamin pyrophosphate. HSCoA = coenzyme A.

OGDH oxoglutarate dehydrogenase complex PDH pyruvate dehydrogenase complex... 

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