1.21.4.5: tetrachlorohydroquinone reductive dehalogenase
This is an abbreviated version!
For detailed information about tetrachlorohydroquinone reductive dehalogenase, go to the full flat file.
Word Map on EC 1.21.4.5
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1.21.4.5
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pentachlorophenol
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dehalogenation
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trichlorohydroquinone
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chlorophenolicum
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s-transferase
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sphingobium
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dithiothreitol
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chlorinate
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sphingomonas
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gst
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maleylacetoacetate
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thiol-disulfide
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glutathione-dependent
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isomerization
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deprotonated
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maleylacetone
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maleylpyruvate
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electrophilic
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cosubstrate
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elementary
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pcp
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chrysosporium
-
aldolase
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theta
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phanerochaete
- 1.21.4.5
- pentachlorophenol
-
dehalogenation
-
trichlorohydroquinone
- chlorophenolicum
- s-transferase
-
sphingobium
- dithiothreitol
-
chlorinate
- sphingomonas
- gst
- maleylacetoacetate
-
thiol-disulfide
-
glutathione-dependent
-
isomerization
-
deprotonated
- maleylacetone
- maleylpyruvate
-
electrophilic
-
cosubstrate
-
elementary
- pcp
-
chrysosporium
- aldolase
- theta
-
phanerochaete
Reaction
Synonyms
PCP hydroxylase, pcpC, TCHQ dehalogenase, tetrachloro-p-hydroquinone reductive dehalogenase, tetrachlorohydroquinone dehalogenase, tetrachlorohydroquinone reductive dehalogenase
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Substrates Products
Substrates Products on EC 1.21.4.5 - tetrachlorohydroquinone reductive dehalogenase
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REACTION DIAGRAM
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme is involved in degradation of pentachlorophenol
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. In addition to trichlorohydroquinone and dichlorohydroquinone, the enzyme also produces substantial amounts of 2,3,5-trichloro-6-S-glutathionylhydroquinone and an unidentified isomer of dichloro-S-glutathionylhydroquinone. Treatment of the purified enzyme with dithiothreitol or use of freshly prepared crude extracts dramatically decreases the formation of S-glutathionylhydroquinone and the unidentified isomer of dichloro-S-glutathionylhydroquinone. 2,3,5-Trichloro-6-S-glutathionylhydroquinone and an unidentified isomer of dichloro-S-glutathionylhydroquinone are produced by enzyme that has undergone some type of oxidative damage and are therefore not physiologically relevant products. The fact that the oxidative damage can be repaired by DTT suggests that a cysteine or methionine residue may be involved
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-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme binds the glutathione involved in the thioldisulfide exchange reaction very poorly and does not alter its pKa in order to improve its nucleophilicity. Remarkably, single-turnover kinetic studies show that the enzyme catalyzes this step by approximately 10000fold
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme uses glutathione but not NADPH, NADH, dithiothreitol, or ascorbic acid as the reducing agent
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The reaction does not involve nucleophilic aromatic substitution
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The reaction proceeds by a rapid equilibrium random sequential kinetic mechanism. Substrate analogues that lack a second hydroxyl group cannot be turned over to products, although they can bind to the active site. The rate of the reaction is strongly influenced by the number of electron withdrawing substituents on the substrate. These findings are consistent with a mechanism that begins with ketonization of the deprotonated substrate to form 2,3,5,6-tetrachloro-4-hydroxycyclohexa-2,4-dienone, followed by 1,4-elimination of HCl to from trichlorobenzoquinone. Subsequently, trichlorobenzoquinone is attacked by glutathione to form a glutathione conjugate
-
-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
the first glutathione is involved in formation of a glutathione conjugate, while the second is involved in the final step of the reaction, a thiol-disulfide exchange reaction that regenerates the free enzyme and forms GSSG. The thiol-disulfide exchange reaction is the rate-limiting step in the reductive dehalogenation reaction under physiological conditions
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-
?
2,3,5,6-tetrachlorohydroquinone + 2 glutathione
2,3,6-trichlorohydroquinone + Cl- + glutathione disulfide
-
-
-
?
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme is involved in degradation of pentachlorophenol, a widely used wood preservative
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme is involved in degradation of pentachlorophenol
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
-
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. Binding of trichlorohydroquinone (TriCHQ) to the active site is followed by rapid deprotonation to form TriCHQ-2 and subsequent formation of 3,5,6-trichloro-4-hydroxycyclohexa-2,4-dienone. Further conversion of 3,5,6-trichloro-4-hydroxycyclohexa-2,4-dienone to 2,6-dichlorohydroquinone proceeds only in the presence of glutathione. Conversion of 3,5,6-trichloro-4-hydroxycyclohexa-2,4-dienone to 2,6-dichlorohydroquinone during the first turnover is quite rapid, occurring at about 25/s when the enzyme is saturated with TriCHQ and glutathione. The rate of subsequent turnovers is limited by the rate of the thiol-disulfide exchange reaction required to regenerate the free enzyme after turnover, a reaction that is intrinsically less difficult, but is hampered by premature binding of the aromatic substrate to the active site before the catalytic cycle is completed
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-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme binds the glutathione involved in the thioldisulfide exchange reaction very poorly and does not alter its pKa in order to improve its nucleophilicity. Remarkably, single-turnover kinetic studies show that the enzyme catalyzes this step by approximately 10000fold
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the enzyme converts tetrachlorohydroquinone to trichlorohydroquinone and trichlorohydroquinone to dichlorohydroquinone. The enzyme uses glutathione but not NADPH, NADH, dithiothreitol, or ascorbic acid as the reducing agent
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
the first glutathione is involved in formation of a glutathione conjugate, while the second is involved in the final step of the reaction, a thiol-disulfide exchange reaction that regenerates the free enzyme and forms GSSG. The thiol-disulfide exchange reaction is the rate-limiting step in the reductive dehalogenation reaction under physiological conditions
-
-
?
2,3,6-trichlorohydroquinone + 2 glutathione
2,6-dichlorohydroquinone + Cl- + glutathione disulfide
-
-
-
?