(S)-1-Phenylethanol dehydrogenase of Azoarcus sp strain EbN1, an enzyme ofanaerobic ethylbenzene catabolism

Kniemeyer, O Heider, J

O. Kniemeyer et J. Heider, (S)-1-Phenylethanol dehydrogenase of Azoarcus sp strain EbN1, an enzyme ofanaerobic ethylbenzene catabolism, ARCH MICROB, 176(1-2), 2001, pp. 129-135

17

INGLESE

Article

Microbiology

ARCHIVES OF MICROBIOLOGY

0302-8933 → ACNP

176

1-2

2001

129 - 135

ISI

0302-8933(200107)176:1-2<129:(DOASS>2.0.ZU;2-C

The initial steps in the anaerobic oxidation of the aromatic hydrocarbon et hylbenzene by denitrifying bacteria are two sequential dehydrogenation reac tions of ethylbenzene to (S)-1-phenylethanol and further to acetophenone. T he enzyme catalysing the second oxidation step, (S)-1-phenylethanol dehydro genase, was analysed in the denitrifying bacterium Azoarcus sp. strain EbN1 . An NAD(+)-dependent 1-phenylethanol dehydrogenase for each of the enantio mers of 1-phenylethanol was identified in this bacterium; the two enzymes w ere induced under different growth conditions. (S)-1-phenylethanol dehydrog enase from ethylbenzene-grown cells was purified and biochemically characte rised. The enzyme is a typical secondary alcohol dehydrogenase and consists of two subunits of 25.5 kDa. The enantioselective enzyme catalyses the oxi dation of (S)-1-phenylethanol or the reduction of acetophenone and is inhib ited by high concentrations of (R)-1-phenylethanol. The enzyme exhibits low apparent K-m values for (S)-1-phenylethanol and acetophenone and is rather substrate-specific, using only a few chemically similar secondary alcohols , such as 1-phenylpropanol and isopropanol.