Phosphoglycerate Kinase
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| - | + | The mechanism of catalysis must be similar to that of hexokinase since the two enzymes both have a similar function and structure. Hexokinase catalyzes the removal of a phosphate group from ATP to glucose. The reaction of PGK removes a phosphate group from the intermediate molecue, 1,3-biphosphoglycerate and transfers it to ADP to form ATP. Once the substrates bind to the active sites, the protein domains swing shut forcing the substrates into correct position for the reaction to proceed. The negatively charged oxygen of the last phosphate group on ADP nucelophillically attacks a phosphate of 1,3-phosphoglycerate. | |
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and display another structure. | and display another structure. | ||
Revision as of 04:18, 1 March 2010
Mechanism of Phosphoglycerate Kinase(PGK) Catalysis
Phosphogylcerate kinase is a crucial enzyme of the glycolysis cycle. This cycle breaks down glucose into pyruvate while generating 2 NADH and 2 ATP molecules. Phosphogylcerate kinase is the seventh enzyme in the cycle which catalyzes the reaction of 1,3-Biphosphoglycerate and ADP to produce 3-Phosphoglycerate and ATP. This method for ATP production is known as substrate level phosphorylation because it produces energy storing ATP molecules with out the use of oxygen, NADH, and an ATPase. The reaction is highly exergonic allowing it to be coupled with the GADPH reaction of the cycle.
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| 3cin, resolution 1.70Å () | |||||||||
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| Ligands: | , , | ||||||||
| Gene: | TM1419, TM_1419 (Thermotoga maritima MSB8) | ||||||||
| Activity: | Inositol-3-phosphate synthase, with EC number 5.5.1.4 | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum, TOPSAN | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
The SCOP classification of PGK is alpha and beta, indicating that is composed of roughly equal alpha and beta sheets. The tertiary stucture, or the overal structure, is that of a bilobed complex. The lobes/domains are clearly connected at only two locations: This enzyme has only one chain, thus its quaternary structure is that of a monomer.
The bilobed nature of the protein is very crucial in the its catlytic function. The active site is broken into two pieces, one on each interior lobe. On one site the ADP-Mg2+ substrate binds and on the other lobe the 1,3-Biphosphoglycerate substrate binds. Upon binding of both substrates at the active sites, the protein's conformation changes such that the two lobes of the protein swing together. The hinge for this conformational change is beta sheet L and the new conformation is formed via a salt bridge between ARG62 and ASP200. This swinging shut of the protein creates an interior hydrophobic chamber that is free of water for the reaction to take place in.
The mechanism of catalysis must be similar to that of hexokinase since the two enzymes both have a similar function and structure. Hexokinase catalyzes the removal of a phosphate group from ATP to glucose. The reaction of PGK removes a phosphate group from the intermediate molecue, 1,3-biphosphoglycerate and transfers it to ADP to form ATP. Once the substrates bind to the active sites, the protein domains swing shut forcing the substrates into correct position for the reaction to proceed. The negatively charged oxygen of the last phosphate group on ADP nucelophillically attacks a phosphate of 1,3-phosphoglycerate.
Replace the PDB id (use lowercase!) after the STRUCTURE_ and after PDB= to load and display another structure.
Proteopedia Page Contributors and Editors (what is this?)
Shane Harmon, Michal Harel, Joel L. Sussman, Brandon Tritle, David Canner, Alexander Berchansky
