Triacylglycerol lipase (Pseudomonas family)
Member of the Pseudomonas lipase family, and an alpha-beta hydrolase superfamily member. Also requires calcium for catalysis to occur. Catalyses the hydrolysis of triglycerides.
Reference Protein and Structure
- Sequence
-
Q05489
(3.1.1.3)
(Sequence Homologues)
(PDB Homologues)
- Biological species
-
Burkholderia glumae (Pseudomonas glumae)
- PDB
-
1tah
- THE CRYSTAL STRUCTURE OF TRIACYLGLYCEROL LIPASE FROM PSEUDOMONAS GLUMAE REVEALS A PARTIALLY REDUNDANT CATALYTIC ASPARTATE
(3.0 Å)
- Catalytic CATH Domains
-
3.40.50.1820
(see all for 1tah)
- Cofactors
- Calcium(2+) (1)
Enzyme Reaction (EC:3.1.1.3)
+
→
+
+
Alternative enzyme names: GA 56, GEH, Meito MY 30, PPL, Takedo 1969-4-9, Tween hydrolase, Tweenase, Tweenesterase, Amano AP, Amano B, Amano CE, Amano CES, Amano P, Amno N-AP, Butyrinase, Cacordase, Capalase L, Glycerol ester hydrolase, Glycerol-ester hydrolase, Heparin releasable hepatic lipase, Hepatic lipase, Hepatic monoacylglycerol acyltransferase, Lipase, Lipazin, Liver lipase, Meito Sangyo OF lipase, Post-heparin plasma protamine-resistant lipase, Salt-resistant post-heparin lipase, Steapsin, Triacetinase, Triacylglycerol ester hydrolase, Tributyrase, Tributyrin esterase, Tributyrinase, Triglyceridase, Triglyceride hydrolase, Triglyceride lipase, Triolein hydrolase, Tween-hydrolyzing esterase,
Enzyme Mechanism
Introduction
This protein is a member of the alpha-beta hydrolase superfamily and is known to function via a classical Ser-His-Asp triad mechanism. Here the histidine of the triad activates the serine, which acts as a nucleophile, forming a covalent intermediate, which then collapses to eliminate the first product. Hydrolysis of the enzyme-substrate bond results in the release of the final product and regeneration of the active site.
Catalytic Residues Roles
| UniProt | PDB* (1tah) | ||
| Leu56 (main-N), Gln127 (main-N) | Leu17(16)B(A) (main-N), Gln88(87)B(A) (main-N) | Form the oxyanion hole that stabilises the negatively charged intermediates and transition states formed. | electrostatic stabiliser |
| Asp302 | Asp263(262)B(A) | Part of the Ser-His-Asp catalytic triad. Activates the histidine. | increase basicity, modifies pKa, electrostatic stabiliser |
| Ser126 | Ser87(86)B(A) | Part of the Ser-His-Asp catalytic triad. Acts as the nucleophile. | covalently attached, nucleofuge, nucleophile, proton acceptor, proton donor |
| His324 | His285(284)B(A) | Part of the Ser-His-Asp catalytic triad. Acts as a general acid/base to activate the serine. | proton acceptor, proton donor |
| Val334 (main-C), Gln330, Asp326, Asp280 | Val295(294)B(A) (main-C), Gln291(290)B(A), Asp287(286)B(A), Asp241(240)B(A) | Forms part of the calcium binding site. | metal ligand |
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file;
y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain;
C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.
Chemical Components
bimolecular nucleophilic addition, proton transfer, intermediate formation, overall reactant used, overall product formed, unimolecular elimination by the conjugate base, native state of enzyme regenerated, intermediate terminatedReferences
- Schrag JD et al. (1997), Structure, 5, 187-202. The open conformation of a Pseudomonas lipase. DOI:10.1016/s0969-2126(97)00178-0. PMID:9032074.
- Chiou S et al. (2009), QSAR Comb Sci, 28, 267-273. QSAR for Inhibition ofPseudomonasSpecies Lipase by 1-Acyloxy-3-N-n-octylcarbamyl-benzenes. DOI:10.1002/qsar.200810031.
Step 1. His285 acts as a general base activating the Ser87 hydroxyl group for nucleophilic attack on the carbonyl carbon of the ester bond. The third component of this catalytic triad- Asp263 acts to increase the basicity of the histidine. The oxyanion intermediate formed is stabilized by the amide groups of Gln88 and Leu17. The calcium ion may also play a role in stabilization.
Download: Image, Marvin FileCatalytic Residues Roles
| Residue | Roles |
|---|---|
| Leu17(16)B(A) (main-N) | electrostatic stabiliser |
| Gln88(87)B(A) (main-N) | electrostatic stabiliser |
| Asp241(240)B(A) | metal ligand |
| Asp287(286)B(A) | metal ligand |
| Gln291(290)B(A) | metal ligand |
| Val295(294)B(A) (main-C) | metal ligand |
| Asp263(262)B(A) | modifies pKa, electrostatic stabiliser, increase basicity |
| Ser87(86)B(A) | proton donor |
| His285(284)B(A) | proton acceptor |
| Ser87(86)B(A) | nucleophile |
Chemical Components
ingold: bimolecular nucleophilic addition, proton transfer, intermediate formation, overall reactant used
Step 2. The tetrahedral intermediate collapses and diacylglycerol is eliminated.
Download: Image, Marvin FileCatalytic Residues Roles
| Residue | Roles |
|---|---|
| Ser87(86)B(A) | covalently attached |
| Leu17(16)B(A) (main-N) | electrostatic stabiliser |
| Gln88(87)B(A) (main-N) | electrostatic stabiliser |
| Asp263(262)B(A) | electrostatic stabiliser |
| Asp241(240)B(A) | metal ligand |
| Asp287(286)B(A) | metal ligand |
| Gln291(290)B(A) | metal ligand |
| Val295(294)B(A) (main-C) | metal ligand |
| His285(284)B(A) | proton donor |
Chemical Components
overall product formed, proton transfer, ingold: unimolecular elimination by the conjugate base
Step 3. His285 activates water for nucleophilic attack and another oxyanion intermediate is formed.
Download: Image, Marvin FileCatalytic Residues Roles
| Residue | Roles |
|---|---|
| Ser87(86)B(A) | covalently attached |
| Leu17(16)B(A) (main-N) | electrostatic stabiliser |
| Gln88(87)B(A) (main-N) | electrostatic stabiliser |
| Asp263(262)B(A) | electrostatic stabiliser |
| Asp263(262)B(A) | increase basicity, modifies pKa |
| Asp241(240)B(A) | metal ligand |
| Asp287(286)B(A) | metal ligand |
| Gln291(290)B(A) | metal ligand |
| Val295(294)B(A) (main-C) | metal ligand |
| His285(284)B(A) | proton acceptor |
Chemical Components
proton transfer, ingold: bimolecular nucleophilic addition
Step 4. The tetrahedral intermediate collapses and Ser87 is eliminated.
Download: Image, Marvin FileCatalytic Residues Roles
| Residue | Roles |
|---|---|
| Leu17(16)B(A) (main-N) | electrostatic stabiliser |
| Gln88(87)B(A) (main-N) | electrostatic stabiliser |
| Asp263(262)B(A) | electrostatic stabiliser |
| Asp241(240)B(A) | metal ligand |
| Asp287(286)B(A) | metal ligand |
| Gln291(290)B(A) | metal ligand |
| Val295(294)B(A) (main-C) | metal ligand |
| Ser87(86)B(A) | nucleofuge |
| His285(284)B(A) | proton donor |
| Ser87(86)B(A) | proton acceptor |
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