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Literature summary for 4.2.1.143 extracted from

  • McGuire, S.M.; Silva, J.C.; Casillas, E.G.; Townsend, C.A.
    Purification and characterization of versicolorin B synthase from Aspergillus parasiticus. Catalysis of the stereodifferentiating cyclization in aflatoxin biosynthesis essential to DNA interaction (1996), Biochemistry, 35, 11470-11486.
    View publication on PubMed
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Inhibitors

Inhibitors Comment Organism Structure
3-(2-hydroxyethyl)-2,3-dihydro-1-benzofuran-2,4-diol competitive Aspergillus parasiticus
versicolorin B
-
 Aspergillus parasiticus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0024
-
 versiconal hemiacetal pH 6.5, 37°C Aspergillus parasiticus

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
78000
-
 2 * 78000, SDS-PAGE Aspergillus parasiticus
140000
-
 gel filtration Aspergillus parasiticus

Organism

Organism UniProt Comment Textmining
Aspergillus parasiticus Q12062
-
-
Aspergillus parasiticus ATCC 56775 Q12062
-
-

Purification (Commentary)

Purification (Comment) Organism
-
 Aspergillus parasiticus

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
1900
-
 pH 6.5, 37°C Aspergillus parasiticus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
additional information enzyme selects from two equilibrating enantiomers of versiconal hemiacetal to cyclize the appropriate antipode to optically pure versicolorin B. By varying the amount of enzyme to a fixed concentration of substrate, the rate of enzymic cyclization can be limited by the intrinsic rate of enantiomerization of the substrate under the conditions of reaction Aspergillus parasiticus ?
-
 ?
additional information enzyme selects from two equilibrating enantiomers of versiconal hemiacetal to cyclize the appropriate antipode to optically pure versicolorin B. By varying the amount of enzyme to a fixed concentration of substrate, the rate of enzymic cyclization can be limited by the intrinsic rate of enantiomerization of the substrate under the conditions of reaction Aspergillus parasiticus ATCC 56775 ?
-
 ?
versiconal hemiacetal i.e. (2S,3S)-2,4,6,8-tetrahydroxy-3-(2-hydroxyethyl)anthra[2,3-b]furan-5,10-dione Aspergillus parasiticus versicolorin B + H2O (3aR,12bS)-8,10,12-trihydroxy-1,2,3a,12b-tetrahydroanthra[2,3-b]furo[3,2-d]furan-6,11-dione, ?
versiconal hemiacetal i.e. (2S,3S)-2,4,6,8-tetrahydroxy-3-(2-hydroxyethyl)anthra[2,3-b]furan-5,10-dione Aspergillus parasiticus ATCC 56775 versicolorin B + H2O (3aR,12bS)-8,10,12-trihydroxy-1,2,3a,12b-tetrahydroanthra[2,3-b]furo[3,2-d]furan-6,11-dione, ?

Subunits

Subunits Comment Organism
dimer 2 * 78000, SDS-PAGE Aspergillus parasiticus

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
2.5
-
 versiconal hemiacetal pH 6.5, 37°C Aspergillus parasiticus

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
4 8 broad Aspergillus parasiticus

pH Range

pH Minimum pH Maximum Comment Organism
4
-
 drastic decline in activity below Aspergillus parasiticus

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.076
-
 3-(2-hydroxyethyl)-2,3-dihydro-1-benzofuran-2,4-diol pH 6.5, 37°C Aspergillus parasiticus

pI Value

Organism Comment pI Value Maximum pI Value
Aspergillus parasiticus isoelectric focusing
-
 4.7