Thermoanaerobium brockii alcohol

Figure 16.4-3. Aldehyde dismutase acitivity of Thermoanaerobium brockii alcohol dehydrogenase (TBADH). A high affinity of the TBADH-NAD+ complex for hydrated acetaldehyde is proposed, explaining the stochiometric acetaldehyde dismutation.

Scheme 2.119 Enantioselective reduction of ketones using Thermoanaerobium brockii alcohol dehydrogenase (TBADH)...

Reagent T, TBADH, Thermoanaerobium brockii alcohol dehydrogenase Keinam E, Hafeli EK, Seth KK, Lamed R (1986) J Am Chem Soc 108 162... 

Other biocatalysts were also used to perform the dynamic kinetic resolution through reduction. For example, Thermoanaerobium brockii reduced the aldehyde with a moderate enantioselectivity [30b,c], and Candida humicola was found, as a result of screening from 107 microorganisms, to give the (Jl)-alcohol with 98.2% ee when ester group was methyl [30dj. 

Alcohol dehydrogenase (TBADH) from Thermoanaerobium brockii [20]... 

Because the direct electrochemical oxidation of NAD(P)H has to take place at an anode potential of + 900 mV vs NHE or more, only rather oxidation-stable substrates can be transformed without loss of selectivity—thus limiting the applicability of this method. The electron transfer between NADH and the anode may be accellerated by the use of a mediator. At the same time, electrode fouling which is often observed in the anodic oxidation of NADH can be prevented. Synthetic applications have been described for the oxidation of 2-hexene-l-ol and 2-butanol to 2-hexenal and 2-butanone catalyzed by yeast alcohol dehydrogenase (YADH) and the alcohol dehydrogenase from Thermoanaerobium brockii (TBADH) repectively with indirect electrochemical... 

Alcohol dehydrogenase-catalyzed reduction of ketones is a convenient method for the production of chiral alcohols. HLAD, the most thoroughly studied enzyme, has a broad substrate specificity and accommodates a variety of substrates (Table 11). It efficiently reduces all simple four- to nine-membered cyclic ketones and also symmetrical and racemic cis- and trans-decalindiones (167). Asymmetric reduction of aliphatic acyclic ketones (C-4-C-10) (103,104) can be efficiently achieved by alcohol dehydrogenase isolated from Thermoanaerobium brockii (TBADH) (168). The enzyme is remarkably stable at temperatures up to 85°C and exhibits high tolerance toward organic solvents. Alcohol dehydrogenases from horse liver and T. brockii... 

Enzyme 1 = Enzyme 2 For example alcohol dehydrogenase from Thermoanaerobium brockii 1,, 9I, Pseudomonas spj6 Lactobacillus kefir[ 1, and Geotrichum candidum120, 211. 

The availability of sufficient quantities of enzymes for crystallization studies has led to the crystal structures been obtained for several dehydrogenases. For example, two tetrameric NADP+-dependent bacterial secondary alcohol dehydrogenases from the mesophilic bacterium Clostridium beijerinckii and the thermophilic bacterium Thermoanaerobium brockii have been crystallized in the apo- and the holo-enzyme forms, and their structures are available in the Protein Data Bank11451. The crystal structure of the alcohol dehydrogenase from horse liver is also available[40 21. 

The alcohol dehydrogenase from Thermoanaerobium brockii is very suitable for the reduction of aliphatic ketones[18, 19L Even very simple aliphatic ketones can be reduced enantioselectively. An interesting substrate size-induced reversal of enantio-selectivity was observed. The smaller substrates (methyl ethyl, methyl isopropyl or methyl cyclopropyl ketones) were reduced to the (R)-alcohols, whereas higher ketones produced the (S -enantiomers. 

Alcohol Dehydrogenase Origin Thermoanaerobium brockii Fluka... 

Another common organism for reduction of the carbonyl group is Thermoanaerobium brockii 111), first mentioned in Section 4.7.A in Table 4.6. Keinan et al. showed that small ketones such as 2-butanone are reduced by T. brockii to give the f/ )-alcohol [2-butanol, 618 in 12% yield and 48% ee, (/ )] but large ketones such as 2-nonanone are reduced to the fS)-alcohol [619, 85% yield and 96% ee, An alcohol... 

The putative binding motif of an NADP -dependent alcohol dehydrogenase of Thermoanaerobium brockii was introduced into XDH from P. stipitis [148]. The resulting enzyme showed a specific activity of 31% of that of the unaltered enzyme and, as above, the affinity for NAD+ decreased ninefold whereas the affinity for NADP+ remained unchanged. When the altered enzyme was expressed together with a xylose reductase in S. cerevisiae, growth was observed on xylose minimal medium plates. 

In 1991, the group of Willetts [13] published one of the first smart combinations of two redox enzymes for the oxidation of a secondary alcohol mediated by an alcohol dehydrogenase (ADH) from Thermoanaerobium brockii and the subsequent Baeyer-Villiger oxidation mediated by the cyclohexanone monooxygenase from Acinetobacter calcoaceticus NCIMB 9871) of the intermediate ketone... 

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