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MetaCyc Compound: diacetyl

Synonyms: 2,3-butanedione, biacetyl, dimethylglyoxal, 2,3-diketobutane, 2,3-dioxobutane, butadione, dimethyl diketone, butanedione

Superclasses: an aldehyde or ketonea ketonea methyl ketone

Diacetyl is an important flavor component in many fermented foods and beverages, including dairy and dairy-like products, beer and wine [Bartowsky04]. It imparts a buttery aroma and flavour, and has an important stylistic role in wine. In beer, diacetyl is considered a spoilage factor. During beer maturation, 2-acetolactate is slowly converted to diacetyl by a chemical, non-enzymatic process, and the diacetyl is converted to acetoin by diacetyl reductase of the yeast cells. for this purpose, purified enzyme is sometimes added to the wort [Diderichsen90].

Chemical Formula: C4H6O2

Molecular Weight: 86.09 Daltons

Monoisotopic Molecular Weight: 86.0367794368 Daltons

diacetyl compound structure


InChI: InChI=1S/C4H6O2/c1-3(5)4(2)6/h1-2H3


Unification Links: CAS:431-03-8, ChEBI:16583, ChemSpider:630, HMDB:HMDB03407, KEGG:C00741, PubChem:650

Standard Gibbs Free Energy of Formation (ΔfG in kcal/mol): -0.013278274Inferred by computational analysis [Latendresse13]

Reactions known to consume the compound:

(R)-acetoin biosynthesis I :
(R)-acetoin + NAD+diacetyl + NADH + H+

(S)-acetoin biosynthesis :
(S)-acetoin + NAD+diacetyl + NADH + H+

Not in pathways:
acetoin + NAD+diacetyl + NADH + H+

Reactions known to produce the compound:

(R)-acetoin biosynthesis I , (S)-acetoin biosynthesis :
(S)-2-acetolactate + an oxidized unknown electron acceptor + H+diacetyl + CO2 + an reduced unknown electron acceptor

methyl ketone biosynthesis :
a 3-oxoacid + H+a methyl ketone + CO2

cuticular wax biosynthesis :
a secondary alcohol + an oxidized unknown electron acceptor → a ketone + an reduced unknown electron acceptor

Not in pathways:
a secondary alcohol + oxygen → a ketone + hydrogen peroxide

Not in pathways:
a nitroalkane + oxygen + H2O → an aldehyde or ketone + nitrite + hydrogen peroxide + H+

In Reactions of unknown directionality:

Not in pathways:
acetoin + NADP+ = diacetyl + NADPH + H+

Not in pathways:
a ketone + NADP+ = an enone + NADPH + H+
a secondary alcohol + an oxidized coenzyme F420 = a ketone + a reduced coenzyme F420
a secondary alcohol + NADP+ = a ketone + NADPH + H+
a secondary alcohol + NAD+ = a ketone + NADH + H+

Enzymes activated by diacetyl, sorted by the type of activation, are:

Activator (Allosteric) of: pyruvate oxidase [Koland82]

Enzymes inhibited by diacetyl, sorted by the type of inhibition, are:

Inhibitor (Mechanism unknown) of: threonine dehydrogenase [Epperly89], 2-amino-3-ketobutyrate CoA ligase [Mukherjee92], acyl-CoA:sn-glycerol-3-phosphate 1-O-acyltransferase [Green84], NAD+-dependent malate dehydrogenase [Rao87], kaempferol 3-O-glucosyltransferase [Owens], myricetin 3-O-glucosyltransferase [Owens], quercetin 3-O-glucosyltransferase [Owens], ferrochelatase [Dailey86]

This compound has been characterized as an alternative substrate of the following enzymes: L-glyceraldehyde reductase, [(S,S)-2,3-butanediol-forming]-(S)-acetoin reductase, L-xylulose reductase, D-glyceraldehyde reductase, acetoin dehydrogenase


Bartowsky04: Bartowsky EJ, Henschke PA (2004). "The 'buttery' attribute of wine--diacetyl--desirability, spoilage and beyond." Int J Food Microbiol 96(3);235-52. PMID: 15454314

Dailey86: Dailey HA (1986). "Purification and characterization of bacterial ferrochelatase." Methods Enzymol 123;408-15. PMID: 3702737

Diderichsen90: Diderichsen B, Wedsted U, Hedegaard L, Jensen BR, Sjoholm C (1990). "Cloning of aldB, which encodes alpha-acetolactate decarboxylase, an exoenzyme from Bacillus brevis." J Bacteriol 172(8);4315-21. PMID: 2198252

Epperly89: Epperly BR, Dekker EE (1989). "Inactivation of Escherichia coli L-threonine dehydrogenase by 2,3-butanedione. Evidence for a catalytically essential arginine residue." J Biol Chem 1989;264(31);18296-301. PMID: 2681195

Green84: Green PR, Bell RM (1984). "The triose-phosphate site of homogeneous reconstituted sn-glycerol-3-phosphate acyltransferase of Escherichia coli." Biochim Biophys Acta 1984;795(2);348-55. PMID: 6383480

Koland82: Koland JG, O'Brien TA, Gennis RB (1982). "Role of arginine in the binding of thiamin pyrophosphate to Escherichia coli pyruvate oxidase." Biochemistry 21(11);2656-600. PMID: 7046791

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Mukherjee92: Mukherjee JJ, Dekker EE (1992). "Inactivation of Escherichia coli 2-amino-3-ketobutyrate CoA ligase by phenylglyoxal and identification of an active-site arginine peptide." Arch Biochem Biophys 299(1);147-53. PMID: 1444446

Owens: Owens DK, McIntosh CA "Identification, recombinant expression, and biochemical characterization of a flavonol 3-O-glucosyltransferase clone from Citrus paradisi." Phytochemistry 70(11-12);1382-91. PMID: 19733370

Rao87: Rao GS, Kong CT, Benjamin RC, Harris BG, Cook PF (1987). "Modification of an arginine residue essential for the activity of NAD-malic enzyme from Ascaris suum." Arch Biochem Biophys 255(1);8-13. PMID: 3592670

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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