Butanediol dehydrogenase

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Butanediol dehydrogenase
Butanediol dehydrogenase
Ribbon model of the meso- 2,3-butanediol dehydrogenase from Klebsiella pneumoniae , according to PDB  1GEG
other names
  • Butane-2,3-diol: NAD + oxidoreductase ( NC-IUBMB )
  • (-) - Butanediol dehydrogenase
  • Aminopropanol dehydrogenase
  • 1-Amino-2-propanol: NAD + oxidoreductase
Cofactor NAD +
Enzyme Classifications
EC, category 1.1.1.4 ,  oxidoreductase
Response type Dehydration
Substrate ( R , R ) -2,3-butanediol + NAD +
Products ( R ) -acetoin + NADH / H +
EC, category 1.1.1.76 ,  oxidoreductase
Response type Dehydration
Substrate ( S , S ) -2,3-butanediol + NAD +
Products ( S ) -acetoin + NADH / H +
Occurrence
Parent taxon bacteria

Butanediol dehydrogenases are enzymes that catalyze the dehydrogenation of 2,3-butanediol to acetoin . These enzymes belong to the family of oxidoreductases , with the hydroxyl group acting as a donor and NAD + as an acceptor . In addition, the ( R , R ) -butanediol dehydrogenase takes part in the metabolism of butyric acid . The enantiomeric substrate with left-handed rotation is converted by ( S , S ) -butanediol dehydrogenase.

Stereoisomeric specificities of 2,3-butanediol dehydrogenases

2,3-Butanediol has a stereoisomeric specificity. Some dehydrogenases oxidize a hydroxy group in the D configuration, while other dehydrogenases oxidize a hydroxy group in the L configuration. Since the meso -2,3-butanediol contains hydroxyl groups in the D - (-) - and L - (+) - configuration, it serves as a substrate for all ( R , R ) -butanediol dehydrogenases. The configuration of acetoin, formed by the oxidation of meso -2,3-butanediol, depends on whether the hydroxyl group in the D - (-) or the L - (+) configuration is oxidized.

The bacterium Bacillus polymyxa contains D - (-) - 2,3-butanediol dehydrogenase. The 2,3-butanediol dehydrogenases of the bacteria Enterobacter aerogenes and Aeromonas hydrophila are L - (+) - dehydrogenases. Bacillus subtilis contains both D - (-) - and L - (+) - dehydrogenases. The configuration of the carbon atom of the 2,3-butanediol that is not oxidized affects the rate of oxidation. Bacteria that use meso- 2,3-butanediol, sodium acetate, or sodium lactate for energy metabolism contain D - (-) - dehydrogenases. In Enterobacter aerogenes , D - (-) - dehydrogenase is preferred as substrate with racemic acetoin, whereas L - (+) - dehydrogenase is preferred as substrate when using carbohydrates .

The presence of various combinations of D - (-) - and L - (+) - dehydrogenases and acetoin racemases can explain the appearance of three isomeric 2,3-butanediols as the end product of the fermentation of carbohydrates.

Catalyzed equilibrium

(R, R) -2,3-butanediol NAD + NADH / H + (R) -acetoin

( R , R ) -2,3-butanediol is oxidized and dehydrated by the ( R , R ) -butanediol dehydrogenase. In addition to the reduction equivalent NADH , ( R ) -acetoin is formed.

(S, S) -2,3-butanediol + NAD + + NADH / H + (S) -acetoin

( S , S ) -2,3-butanediol is oxidized and dehydrated by the ( S , S ) -butanediol dehydrogenase. In addition to the reduction equivalent NADH , ( S ) -acetoin is formed.

Irreversible reduction

( S , S ) -Butanediol dehydrogenase can also catalyze the irreversible reduction of diacetyl to ( S ) -acetoin:

Diacetyl + NADH + H + + NAD + (S) -acetoin

Individual evidence

  1. ^ Mary B. Taylor, Elliot June: Stereoisomeric specificities of 2,3-butanediol dehydrogenases . In: Biochimica et Biophysica Acta . 39, No. 3, April 22, 1960, pp. 338-457. doi : 10.1016 / 0006-3002 (60) 90197-9 . PMID 13837186 .