Get   for     ? 
 Site search     ? 
Catalytic Site Atlas Version 2.2.12
Find Annotated Site: PDB code:
Swiss-Prot code:
EC number:
Help
CSA entry for 1zoi
Original Entry
Title:
Hydrolase
Compound:
Esterase
Mutant:
No
UniProt/Swiss-Prot:
Q3HWU8-Q3HWU8_PSEPU
EC Class:
3.1.-.-
Other CSA Entries:
Overview of all sites for 1zoi
Homologues of 1zoi
Entries for UniProt/Swiss-Prot: Q3HWU8
Entries for EC: 3.1.-.-
Other Databases:
PDB entry: 1zoi
PDBsum entry: 1zoi
UniProt/Swiss-Prot: Q3HWU8
IntEnz entry: 3.1.-.-
Literature Report:
Introduction:
Esterase (EST), isolated from Pseudomonas putida, catalyses the hydrolysis of methyl esters. Of particular interest is the stereoselective hydrolysis of DL-beta-acetylthioisobutyrate acid (DL-MATI) to D-beta-acetylthioisobutyric acid (DAT). This is because DAT is an important intermediate in the synthesis of the medicinally important angiotensin-converting enzyme inhibitors. The mechanism of action of EST is similar to the serine protease mechanism.
Mechanism:
His256 deprotonates Ser97 and is stabilised by Asp227. Ser97 is then involved in nucleophilic attack on the carbonyl carbon of D-MALTI. The resulting tetrahedral oxyanion is stabilised by hydrogen bonds to the backbone amines of Trp31 and Thr98, which together form the oxyanion hole. The intermediate collapses to eliminate methoxide, which is protonated by His256. His256 then deprotonates water and is again stabilised by Asp227. The resulting hydroxide is involved in nucleophilic attack on the carbonyl carbon of the acylenzyme intermediate. The tetrahedral intermediate is stabilised by the oxyanion hole and then collapses to eliminate Ser97, which is protonated by His256, and to form DAT.
Sites:

Click to Display Catalytic Site (Get help with this section)
Found by:
Literature reference 

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
TRPA 31 31Backbone amide
ElectrostaticTransition state
Trp31 forms part of the oxyanion hole and stabilises the tetrahedral intermediate by hydrogen bonding to the alkoxide.
Evidence from paper Evidence concerns Evidence type
PubMed ID 12475199 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position hypothetical)
PubMed ID 16321951 Current protein Computer modelling

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
SERA 97 97Sidechain
ModifiedSubstrate
NucleophileSubstrate
Ser97 is deprotonated by His256 and then acts as the nucleophile for attack on the carbonyl of the ester. It is the leaving group in the deacylation reaction and is protonated by His256.
Evidence from paper Evidence concerns Evidence type
PubMed ID 16321951 Current protein Conservation of residue
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position hypothetical)

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
THRA 98 98Backbone amide
ElectrostaticTransition state
Thr98 forms part of the oxyanion hole and stabilises the tetrahedral intermediate by hydrogen bonding to the alkoxide.
Evidence from paper Evidence concerns Evidence type
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position hypothetical)
PubMed ID 12475199 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism
PubMed ID 16321951 Current protein Computer modelling

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
ALAA 122 122Backbone carbonyl
ElectrostaticResidue
The backbone carbonyl of Ala122 forms a hydrogen bond to the epsilon-1 C-H of His256. This weakens the epsilon-2 N-H bond in the protonated histidine, assisting general acid catalysis.
Evidence from paper Evidence concerns Evidence type
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position known)
PubMed ID 8051710 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
ASPA 227 227Sidechain
ElectrostaticResidue
Asp227 forms a hydrogen bond to the delta-1 N-H of His256. This stabilises the protonated state of His256.
Evidence from paper Evidence concerns Evidence type
PubMed ID 10404588 Current protein Conservation of residue
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position hypothetical)
PubMed ID 12475199 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
HISA 256 256Sidechain
Acid/baseResidue
Acid/baseWater
Acid/baseSubstrate
His256 acts as a general acid and a general base during the reaction. It deprotonates the nucleophiles (Ser97 and water) and protonates the leaving groups (methoxide and deprotonated Ser97).
Evidence from paper Evidence concerns Evidence type
PubMed ID 16321951 Current protein Residue is positioned appropriately (ligand position hypothetical)
PubMed ID 10404588 Current protein Conservation of residue
PubMed ID 8051710 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism
PubMed ID 12475199 Related protein: UniProt P00766 Structural similarity to homologue of known mechanism
Notes:

References:
Which EBI biological databases are available and how do I access them? EBI Site Map