Benzyl alcohol dehydrogenase

This pathway is supported by the demonstration of benzyl alcohol dehydrogenase, benzaldehyde dehydrogenase, benzoyl-CoA ligase, and benzoyl-CoA reductase activities in cell extracts (Biegert and Fuchs 1995). The benzyl alcohol dehydrogenase from benzyl alcohol-grown cells was similar in many of its properties to those from the aerobic bacteria Acinetobacter calcoaceticus and Pseudomonas putida (Biegert et al. 1995). 

Biegert T, U Altenschmidt, C Eckerskorn, G Euchs (1995) Purification and properties of benzyl alcohol dehydrogenase from a denitrifying Thauera sp. Arch Microbiol 163 418-423. 

Confirmation of this proposed pathway was established by Altenschmidt Fuchs (1991, 1992) in their study of the biochemistry of toluene decay by the denitrifying Pseudomonas sp. strain K172. These investigators confirmed the presence of benzyl alcohol dehydrogenase, benzaldehyde dehydrogenase, and benzoyl-CoA synthetase in cell-free extracts of this isolate. Further, [14C]benzyl... 

Benzyl alcohol Benzaldehyde Benzyl alcohol dehydrogenase Lact. plantamm... 

Benzyl alcohol can be produced from benzaldehyde (S) by a dehydrogenation reaction catalyzed by yeast alcohol dehydrogenase (YADH). Nikolova et al. (1995) obtained initial-rate data for this reaction using immobilized YADH immersed in iso-octane with 1% v/v water. The following data were obtained ... 

Hydroxylation of the benzylic methyl group of tolbutamide, the preferred site of oxidative attack by CYP2C9 (22), generates hydroxytolbutamide. Hydroxytolbutamide is rapidly oxidized by other enzymes, presumably aldehyde oxidase and/or alcohol dehydrogenase (ALD), to form the major isolated metabolite, the benzoic acid analog. 

Deviations from equation (57) have also been used to demonstrate that tunnelling is important in the enzyme-catalysed oxidation of benzyl alcohol to benzaldehyde by NAD+ and yeast alcohol dehydrogenase (YADH) (reaction (60)) (Cha et al., 1989 Klinman, 1991). 

Table 40 The primary and secondary deuterium-tritium and hydrogen-tritium KIEs for the oxidation of benzyl alcohol to benzaldehyde with NAD+ and yeast alcohol dehydrogenase at 25°C.a...

Yeast alcohol dehydrogenase, catalysis of oxidation by NAD of benzyl alcohol equilibrium interconversion of benzyl alcohol and benzaldehyde... 

A few years later, Cha, Murray and Klinman published a report on isotope effects in the redox interconversion of benzyl alcohol-benzaldehyde/NAD -NADH, with catalysis by yeast alcohol dehydrogenase. This article effected among biochemists... 

Experiments with the oxidation of benzyl alcohol by NAD, catalyzed by yeast alcohol dehydrogenase, yielded =. 12 —. 16 (standard... 

Horse liver alcohol dehydrogenase, F93W mutant with 1224 also mutated to G,A,V,L. hydride transfer from benzyl alcohol to NAD Heterotetrameric sarcosine oxidase of Arthrobacter sp. 1-IN, proton transfer from adduct of FAD with sarcosine-(CH3) and sarcosine-(CD3)... 

Fig. 6 Illustration from Chin and Klinman. Increased catalytic activity of horse-liver alcohol dehydrogenase in the oxidation of benzyl alcohol to benzaldehyde by NAD, measured by cat/ M (ordinate), correlates with the Swain-Schaad exponent for the -secondary isotope effect (abscissa), for which values above about four are indicators of tunneling. This is a direct test of the hypothesis that tunneling in the action of this enzyme contributes to catalysis. As the rate increases by over two orders of magnitude and then levels off, the anomalous Swain-Schaad exponents also increase and then level off. Reproduced from Ref. 28 with the permission of the American Chemical Society.

Isotope effects have also been applied extensively to studies of NAD+/NADP+-linked dehydrogenases. We typically treat these enzymes as systems whose catalytic rates are limited by product release. Nonetheless, Palm clearly demonstrated a primary tritium kinetic isotope effect on lactate dehydrogenase catalysis, a finding that indicated that the hydride transfer step is rate-contributing. Plapp s laboratory later demonstrated that liver alcohol dehydrogenase has an intrinsic /ch//cd isotope effect of 5.2 with ethanol and an intrinsic /ch//cd isotope effect of 3-6-4.3 with benzyl alcohol. Moreover, Klin-man reported the following intrinsic isotope effects in the reduction of p-substituted benzaldehydes by yeast alcohol dehydrogenase kn/ko for p-Br-benzaldehyde = 3.5 kulki) for p-Cl-benzaldehyde = 3.3 kulk for p-H-benzaldehyde = 3.0 kulk for p-CHs-benzaldehyde = 5.4 and kn/ko for p-CHsO-benzaldehyde = 3.4. 

Human polymorphisms in several enzymes involved in toluene metabolism are known. In Mongoloid populations, deficiency in the low form of aldehyde dehydrogenase H2 (ALDH2) is common approximately half of the Japanese population lacks this enzyme. In ALDH2-deficient exposed workers, an increased level of benzyl alcohol was found, but benzaldehyde was not detectable urinary excretion of hippurate was decreased in the deficient individuals. The CYPlAl polymorphism, alcohol consumption and smoking were all associated with decreased hippurate excretion, but the interdependence was too complex to allow detailed conclusions on the mechanisms to be drawn (Kawamoto et al., 1995). 

When FI is replaced by PQQ (pyrroloquinolinequinone), a novel heterocyclic o-quinone cofactor that was first isolated and identified from methanol dehydrogenase of methylotrophic bacteria in 1979 [68], the photochemical oxidation of benzyl alcohols occurs efficiently without HC104 in MeCN [69] ... 

The reduction of ( )-2-, ( )-3- and ( )-4-cinnamoylpyridines by 1,4-dihydropyridines to give dihydro ketones has also been shown to be catalyzed by zinc(II) and magnesium(II).527 Kinetic measurements show that the rate of reduction is fastest in the case of the 2-isomer where the metal is simultaneously complexed with the nitrogen and oxygen donors. A very fast zinc-catalyzed reduction of pyridine-2-carbaldehyde by the alcohol dehydrogenase coenzyme model JV,JV -diethyl-N-benzyl-l,4-dihydronicotinamide (170) has also been described.528... 

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