Dehydrogenase structural features

For example, liver alcohol dehydrogenase was crystallized as the enzyme N AD1 p-bromobenzyl alcohol complex with saturating concentrations of substrates in an equilibrium mixture51b and studied at low resolution. Transient kinetic studies or direct spectroscopic determinations led to the conclusion that the internal equilibrium (E NAD alcohol = E NADH aldehyde) favors the NAD1 alcohol complex.52 Subsequently, the complex was studied at higher resolution, and the basic structural features were confirmed with a... 

Evaluate the frictional ratio by taking the partial specific volume to be 0.735 g cm- 3. Deduce the structural features of the dehydrogenase. 

An important structural feature, common to both metal-sulfur enzyme centers and (hypothetical) low molecular weight competitive catalysts, certainly is the sulfur coordination of the metals. The type of donor atom represents the most basic structural feature of any metal complex. Functional features indispensable for competitive catalysts are determined by Eq. 44. It expresses the hydrogenase, CO dehydrogenase, and nitrogenase reactions in their most general form. 

Do particular structural features fulfil similar functions in different dehydrogenases ... 

Crystal structures are known from a putative yeast CAD (Valencia et al, 2004), an aspen sinapyl alcohol dehydrogenase (SAD Bomati and Noel, 2005) and a zinc-dependent CAD (AtCAD5) from Arabidopsis thaliana. The latter was solved in the apo-form and together with NADP and the structure of AfCAD4 accordingly modelled (Youn et al., 2006a). The structural features... 

The two-domain, structural motif in FNR represents a common structural feature in a large class of enzymes that catalyze electron transfer between a nicotinamide dinucleotide molecule and a one-electron carrier. Beside the photosynthetic electron-transfer enzyme, others non-photosynthetic ones include flavodoxin reductase, sulfite reductase, nitrate reductase, cytochrome reductase, and NADPH-cyto-chrome P450 reductase. FNR belongs to the group of so-called dehydrogenases-electron transferases, i.e., flavoproteins that catalyze electron transfer from two, one-electron donor molecules to a single two-electron acceptor molecule. 

Structural Features of Amino Acid Dehydrogenases (AADHs)... 

A low enantiomeric excess of a reduced product can result from the inability of the oxidoreduc-tase to recognize the structural features of the substrate enantio- and diastereoselectively45. By far the more common case is the competition of two or more enzymes with different enantiose-lectivities and Michaelis constants for the substrate. Yeast cells not only contain yeast alcohol dehydrogenase but several enzymes that arc able to catalyze reductions. At least three different enzymes capable of reducing /i-keto esters have been purified, of which two have D- and one has L-selectivity62-65. Yeast alcohol dehydrogenase has a rather narrow selectivity for short-chain alcohols and aldehydes and certainly is not the catalyst in many of the reductions performed with yeasts. 

The enzymes of the TCA cycle rely heavily on coenzymes for their catalytic function. Isocitrate dehydrogenase and malate dehydrogenase use NAD as a coenzyme, and succinate dehydrogenase uses FAD. Citrate synthase catalyzes a reaction that uses a CoA derivative, acetyl CoA. The a-ketoglutarate dehydrogenase complex uses thiamine pyrophosphate, lipoate and FAD as bound coenzymes, and NAD and CoASEl as substrates. Each of these coenzymes has unique structural features that enable it to fulfill its role in the TCA cycle. 

Aijunan P, Sax M, Brunskill A et al (2006) A thiamin-bound, pre-decaiboxylation reaction intermediate analogue in the pymvate dehydrogenase El subunit induces large scale disorder-to-order transformations in the enzyme and reveals novel structural features in the covalently bound adduct J Biol Chem 281 15296-15303... 

Structural and Kinetic Features of Alcohol and Aldehyde Dehydrogenase I 421... 

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