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Purification and properties of two oxidoreductases catalyzing the enantioselective reduction of diacetyl and other diketones from baker's yeast.
- Source :
-
European journal of biochemistry [Eur J Biochem] 1990 Feb 22; Vol. 188 (1), pp. 165-74. - Publication Year :
- 1990
-
Abstract
- The NADPH-linked diacetyl reductase system from the cytosolic fraction of Saccharomyces cerevisiae has been resolved into two oxidoreductases catalyzing irreversibly the enantioselective reduction of diacetyl (2,3-butanedione) to (S)- and (R)-acetoin (3-hydroxy-2-butanone) [so-called (S)- and (R)-diacetyl reductases] (EC 1.1.1.5) which have been isolated to apparent electrophoretical purity. The clean-up procedures comprising streptomycin sulfate treatment, Sephadex G-25 filtration, DEAE-Sepharose CL-6B column chromatography, affinity chromatography on Matrex Gel Red A and Superose 6 prep grade filtration led to 120-fold and 368-fold purifications, respectively. The relative molecular mass of the (R)-diacetyl reductase, estimated by means of HPLC filtration on Zorbax GF 250 and sodium dodecyl sulfate/polyacrylamide gel electrophoresis, was 36,000. The (R)-enzyme was most active at pH 6.4 and accepted in addition to diacetyl C5-, C6-2,3-diketones, 1,2-cyclohexanedione, 2-oxo aldehydes and short-chain 2- and 3-oxo esters as substrates. The enzyme was characterized by high enantioselectivity and regiospecificity. The Km values for diacetyl and 2,3-pentanedione were determined as 2.0 mM. The Mr of the (S)-diacetyl reductase was determined as 75,000 by means of HPLC filtration of Zorbax GF 250. The enzyme decomposed into subunits of Mr 48,000 and 24,000 on sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The optimum pH was 6.9. The purified (S)-enzyme reduced stereospecifically a broad spectrum of substrates, comprising 2,3-, 2,4- and 2,5-diketones, 2-oxo aldehydes, 1,2-cyclohexanedione and methyl ketones as well as 3-, 4- and 5-oxo esters. The 2,3- and 2,4-diketones are transformed to the corresponding (S)-2-hydroxy ketones; 2,5-hexanedione, however, was reduced to (S,S)-2,5-hexanediol. The Km values for diacetyl and 2,3-pentanedione were estimated as 2.3 and 1.5 mM, respectively. Further characterization of the (S)-diacetyl reductase revealed that it is identical with the so-called '(S)-enzyme', involved in the enantioselective reduction of 3-, 4- and 5-oxo esters in baker's yeast.
- Subjects :
- Acetoin Dehydrogenase antagonists & inhibitors
Chromatography, Affinity
Chromatography, Gas
Chromatography, Gel
Hydrogen-Ion Concentration
Magnetic Resonance Spectroscopy
Mass Spectrometry
Oxidoreductases antagonists & inhibitors
Saccharomyces cerevisiae metabolism
Stereoisomerism
Substrate Specificity
Acetoin Dehydrogenase isolation & purification
Alcohol Oxidoreductases isolation & purification
Butanones metabolism
Diacetyl metabolism
Ketones metabolism
Oxidoreductases isolation & purification
Pentanones metabolism
Saccharomyces cerevisiae enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 0014-2956
- Volume :
- 188
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- European journal of biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 2180695
- Full Text :
- https://doi.org/10.1111/j.1432-1033.1990.tb15384.x