ADH enzyme

Multiple-enzyme conversion of CO2 to formate, then formaldehyde, then methanol by FateDH, FaldDH, and ADH Enzymes loaded in CaC03 followed by LbL deposition and dissolution of core, then encapsulation into a gel bead... 

Microbial reduction has been recognized for decades as a laboratory method of preparing alcohols from ketones with exquisite enantioselectivity. The baker s yeast system represents one of the better known examples of biocatalysis, taught on many undergraduate chemistry courses. Numerous other microorganisms also produce the ADH enzymes (KREDs) responsible for asymmetric ketone reduction, and so suitable biocatalysts have traditionally been identified by extensive microbial screening. Homann et have... 

For this type of C-C bond formation both stereoisomers of the hydroxyphenyl-propanone can be obtained using either the BFD mentioned above or the benz-aldehyde lyase (BAL). Both of these enzymes are dependent on thiamine diphosphate (ThDP) as cofactor [22]. For the enantioselective reduction of the intermediate also, both stereoisomers can be obtained by using two different ADH enzymes. Thus all four possible stereoisomers of the diol can be obtained in high optical purity (see Scheme. 3.1.1) [23]. 

The treatment for methanol or ethylene glycol poisoning is the same. The patient is given intravenous infusions of diluted ethanol. The ADH enzyme is swamped by all the ethanol, allowing time for the kidneys to excrete most of the methanol (or ethylene glycol) before it can be oxidized to formic acid (or oxalic acid). This is an example of competitive inhibition of an enzyme. The enzyme catalyzes oxidation of both ethanol and methanol, but a large quantity of ethanol ties up the enzyme, allowing time for excretion of most of the methanol before it is oxidized. 

Aldehydes, especially the longer chain saturated and branched chain aldehydes (i.e., propanal, butanal, 2-methyl-1-propanal, 2-methyl-1-butanal, and 3-methyl-1-butanal) are also intermediates in the formation of fusel oils. These pathways involve anabolic metabolism of sugars or transamination of amino acids. During ethanol fermentation, the aldehydes may be reduced to the corresponding alcohols by ADH enzymes and excreted into the media. Herraiz et al. (19) found that longer chain aldehydes were not as readily reduced and excreted by the yeast, e.g., 35% reduction was observed for pentanal compared to 3% reduction for decanal. 

Neither of the ADH enzymes is isolated as DPN complexes, but each has a strong and characteristic affinity for the reduced and oxidized forms of the coenzyme (Velick, 1954). The O.D. 280/260 ratio measures protein and nucleotide components of a particular ADH preparation, and a high ratio of a pure protein denotes removal of DPN or DPNH from the apoen-zyme. 

A chronic alcoholic has induced more ADH enzyme to be present to handle large amounts of imbibed ethanol, so requires more ethanol "antidote" molecules to act as a competitive inhibitor to "tie up" the extra enzyme molecules. 

I 70 Nuclear Tunneling in the Condensed Phase Hydrogen Transfer in Enzyme Reactions Table 10.2. Kinetic isotope effect data for various ADH enzymes ). 

DOLFERUS, R., OSTERMAN, J.C., PEACOCK, W.J., DENNIS, E.S., Cloning of the Arabidopsis and rice fomaldehyde dehydrogenase genes Implications for the origin of plant ADH enzymes. Genetics, 1997,146, 1131-1141. 

Given the recent emergence of microfluidic fuel ceU architectures, only a few microfluidic biofuel cells with biological catalysts have been reported to date. The first microfluidic biofuel cell with enzymes immobilized in a microchannel was introduced by Moore et al. [8]. Alcohol dehydrogenase (ADH) enzymes were immobilized onto a carbon microelectrode placed in a 100 pm deep microchannel. A thin film of methylene green, which is an... 

Scheme 5.26 Synthesis of (R)-heptanol and heptanone by P450 BM3 mutants and (S)-specific ADH with concomitant NADH regeneration. The P450 BM3 mutant was engineered for NADH preference, resulting in cofactor compatibility of P450 BM3 and ADH enzyme (both NAD(H) dependent).

Yoshii, H., Buche, F Takeuchi, N Terrol, C., Ohgawara, M., Furuta, T, 2008. Effects of protein on retention of ADH enzyme activity encapsulated in trehalose matrices by spray drying.. Food Eng. 87 34-39. 

Gelbart et al. (1974) demonstrated that all null mutations at the rosy locus lie within the structural gene for xanthine dehydrogenase. Similarly, Schwartz and So-fer (1976) noted that 11 of 16 ADH-negative mutations (induced by ethyl methane sulfonate) produce an inactive ADH enzyme. It is possible that the remaining five mutations are also located in the ADH locus. The authors have supposed the following possible explanations for the data observed ... 

Experimental evidence caused us to suspect that Komagataeibacter strains share most of the resistance mechanisms shown by Acetobacter sp., although they also must develop specific strategies that enable tolerance to the drastic conditions of submerged vinegar production. We have already addressed the higher activity and stability of PQQ-ADH enzyme compared with that in Acetobacter sp., as well as their specialized lipid membrane composition (Trcek et al. 2006, 2007). 

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