EC Number   |
Substrates |
Organism |
Products |
Reversibility |
|---|
    4.2.1.143 | more |
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 |
? |
- |
? |
| 4.2.1.143 | more |
in addition, enzyme catalyzes the conversion of 5'-oxoaverantin to (2'S,5'S)-averufin, reaction of EC 4.2.1.142, 5'-oxoaverantin cyclase |
Aspergillus parasiticus |
? |
- |
? |
| 4.2.1.143 | more |
racemic versiconal hemiacetate or racemic versiconal leads exclusively to formation of (1'R,2'S)-(-)-versicolorin B. Only (1'R,2'S)-(-)-versicolorin B, and not (1'S,2'R)-(+)antipode, serves as a substrate for desaturase activity in the following reaction of the aflatoxin biosynthetic pathway. Thus the stereoconfiguration of bis-furan moiety in aflatoxin molecules is determined by the cyclase enzyme catalyzing the reaction from versiconal to versicolorinB. Nonenzymatic racemization in both the (2'R)- and (2'S)-versiconal hemiacetate enantiomers is dependent upon the temperature and alkaline conditions |
Aspergillus parasiticus |
? |
- |
? |
| 4.2.1.143 | more |
in addition, enzyme catalyzes the conversion of 5'-oxoaverantin to (2'S,5'S)-averufin, reaction of EC 4.2.1.142, 5'-oxoaverantin cyclase |
Aspergillus parasiticus NRRL 2999 |
? |
- |
? |
| 4.2.1.143 | more |
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 |
? |
- |
? |
| 4.2.1.143 | more |
racemic versiconal hemiacetate or racemic versiconal leads exclusively to formation of (1'R,2'S)-(-)-versicolorin B. Only (1'R,2'S)-(-)-versicolorin B, and not (1'S,2'R)-(+)antipode, serves as a substrate for desaturase activity in the following reaction of the aflatoxin biosynthetic pathway. Thus the stereoconfiguration of bis-furan moiety in aflatoxin molecules is determined by the cyclase enzyme catalyzing the reaction from versiconal to versicolorinB. Nonenzymatic racemization in both the (2'R)- and (2'S)-versiconal hemiacetate enantiomers is dependent upon the temperature and alkaline conditions |
Aspergillus parasiticus NIAH-26 |
? |
- |
? |
| 4.2.1.143 | versiconal |
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 |
? |
| 4.2.1.143 | versiconal |
i.e. (2S,3S)-2,4,6,8-tetrahydroxy-3-(2-hydroxyethyl)anthra[2,3-b]furan-5,10-dione |
Aspergillus parasiticus NIAH-26 |
(-)-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 |
? |
| 4.2.1.143 | versiconal |
- |
Aspergillus parasiticus |
versicolorin B + H2O |
- |
? |
| 4.2.1.143 | versiconal |
- |
Aspergillus flavus |
versicolorin B + H2O |
- |
? |
