3.3.2.13: chorismatase
This is an abbreviated version!
For detailed information about chorismatase, go to the full flat file.
Word Map on EC 3.3.2.13
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3.3.2.13
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3-hydroxybenzoic
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polyketide
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starter
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shikimate
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campestris
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macrocyclic
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methylene
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xanthomonas
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yellow
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nonconserved
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rapamycin
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hygroscopicus
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arene
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xanthomonadins
- 3.3.2.13
-
3-hydroxybenzoic
- polyketide
-
starter
- shikimate
- campestris
-
macrocyclic
-
methylene
- xanthomonas
- yellow
-
nonconserved
- rapamycin
- hygroscopicus
- arene
-
xanthomonadins
Reaction
Synonyms
CH-fkbo, chorismatases/chorismate hydrolase, chorismate/3,4-dihydroxycyclohexa-1,5-dienoate synthase, fkbO, rapK
ECTree
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Reaction
Reaction on EC 3.3.2.13 - chorismatase
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chorismate + H2O = (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate
catalytic mechanism, the two carboxyl groups of chorismate form a H-bond network with residues R228, Y215, Y155, and R162. These H-bonds are maintained during the whole catalytic process, which may play a role in stabilizing the negative charged substrate. The protonated E338 builds a strong H-bond with the 4-OH of chorismate. The distance between HA of E338 and C3' of chorismate is 4.00 A. Two water molecules enter the reactive center, which may function as mediators in the catalytic reaction. The reaction steps are protonation of methylene group, followed by nucleophilic attack of carbocation by (activated) water molecule W1, and cleavage of C2'-O8 bond
chorismate + H2O = (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate
for the CH-FkbO subfamily, an isochorismatase-like hydrolysis mechanism is suggested where the acidic active site residue E338FkbO initially protonates the C3' of chorismate. This resulting carbocation intermediate is nucleophilically attacked by (activated) water leading to the formation of an unstable tetrahedral intermediate (hemiketal), which decomposes spontaneously into the products 3,4-trans-dihydroxy-cyclohexa-1,5-dienecarboxylate and pyruvate. Hydrolysis reaction mechanism analysis, overview
chorismate + H2O = (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate
reaction steps are: 1. the protonation of the methylene group of chorismate, 2. nucleophilic attack by activated water at the C2' carbocation, and 3. the elimination of pyruvate