Sandbox Reserved 1731
From Proteopedia
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| - | This is a sample scene created with SAT to <scene name="/12/3456/Sample/1">color</scene> by Group, and another to make <scene name="/12/3456/Sample/2">a transparent representation</scene> of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes. | ||
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
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Revision as of 22:57, 8 November 2022
| This Sandbox is Reserved from August 30, 2022 through May 31, 2023 for use in the course Biochemistry I taught by Kimberly Lane at the Radford University, Radford, VA, USA. This reservation includes Sandbox Reserved 1730 through Sandbox Reserved 1749. |
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Contents |
Photinus pyralis luciferase
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Luciferases are enzymes that catalyzes the light-producing chemical reactions of bioluminescent organisms, such as fireflies and bacteria. Photinus pyralis luciferase, which is the specific luciferase protein found in the common eastern firefly, causes an enzymatic reaction between the enzyme (luciferase) and the substrate (luciferin). This reaction is an oxidation process with molecular oxygen and its conversion into chemical energy, which causes the bursts of light.
Structure
The overall structure of luciferase is an asymmetrical monomer. It is composed of two domains specified as the N-terminal and C-terminal. The N-terminal domain consists of a beta-barrel and two beta-sheets flanked by alpha-helices to form a five layer structure α-β-α-β-α structure. The C-terminal domain consists of five beta-strands and three alpha-helices, which is folded into a compact structure that is connected to the N-terminus domain by a disordered loop. Luciferase is composed of 550 amino acids residues in a single polypeptide chain with a peroxisome targeting signal sequence of -Ser-Lys-Leu (-SKL) at C-terminus. The overall structure of luciferase contains alpha helices and beta-barrels.
Function
Luciferase proteins act as enzymes to to produce bursts of light through oxidation reactions of the substrate, luciferin. The reaction formula is:
ATP + firefly D-luciferin + O2 ↔ AMP + CO2 + diphosphate + firefly oxyluciferin + hnu
The reaction begins with the formation of an acid anhydride between the carboxylic group of D-firefly luciferin and AMP, with the release of diphosphate. An oxygenation follows, with the release of the the AMP group group and formation of a very short-lived peroxide that cyclizes into a dioxetanone structure, which collapses, releasing a CO2 molecule. The spontaneous breakdown of the dioxetanone (rather than the hydrolysis of the hydrolysis of the adenylate) releases the energy (about 50 kcal/mole) that is necessary to generate the excited state of oxyluciferin. The excited luciferin then emits a photon, returning to its ground state. The enzyme has a secondary acyl-CoA ligase activity when acting on L-firefly luciferin.
Biological Application
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