Sandbox Reserved 1844: Difference between revisions
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=== Catalytic Triad === | === Catalytic Triad === | ||
LCC catalyzes the breakdown of PET using a classic serine hydrolase mechanism involving a <scene name='10/ | LCC catalyzes the breakdown of PET using a classic serine hydrolase mechanism involving a <scene name='10/1075247/Catalytic_triad3_w_label/3'>Catalytic Triad</scene> of Ser165, His242, and Asp210. The reaction begins when His242 deprotonates Ser165, which activates it as a nucleophile. Ser165 then attacks the carbonyl carbon of an ester bond in the PET polymer. This forms a tetrahedral intermediate. This intermediate is stabilized by an oxyanion hole. The oxyanion hole is formed by the backbone amides of Met166 and Tyr95. The intermediate collapses; one product is released and an acyl-enzyme intermediate is formed. A water molecule, activated by His242, then attacks the acyl-enzyme, releasing the second product and resetting the enzyme’s active site. | ||
[[Image:CH464 PyMOL Presentation Mechanism.jpeg|800 px|right|thumb|Figure 1: Ester bond hydrolysis by LCC. LCC catalyzes ester hydrolysis through a mechanism involving the catalytic triad of Asp210, His242, and Ser165. Asp210 and His242 activate Ser165, which then performs a nucleophilic attack on the ester carbonyl carbon to form a tetrahedral intermediate. This intermediate breaks down, which leads to ester bond cleavage and product release, with the main chain nitrogens of Met166 and Tyr95 acting as an oxyanion hole for transition state stabilization.]] | [[Image:CH464 PyMOL Presentation Mechanism.jpeg|800 px|right|thumb|Figure 1: Ester bond hydrolysis by LCC. LCC catalyzes ester hydrolysis through a mechanism involving the catalytic triad of Asp210, His242, and Ser165. Asp210 and His242 activate Ser165, which then performs a nucleophilic attack on the ester carbonyl carbon to form a tetrahedral intermediate. This intermediate breaks down, which leads to ester bond cleavage and product release, with the main chain nitrogens of Met166 and Tyr95 acting as an oxyanion hole for transition state stabilization.]] | ||
=== Ligand Binding Pocket === | === Ligand Binding Pocket === | ||
<scene name='10/1075246/4eb0_with_colored_ligand_stick/2'>TextToBeDisplayed</scene> | |||
The <scene name='10/1075246/4eb0_with_colored_ligand_stick/1'>substrate-binding site</scene> of LCC is a long, mainly hydrophobic groove that accommodates PET chains. This groove includes three subsites—designated −2, −1, and +1—that interact with specific PET units near the scissile ester bond. Hydrophobic residues such as F125, V212, M166, and F243 line the groove and facilitate binding by interacting with the aromatic rings of the PET molecule. These interactions help align the substrate in the correct position for catalysis. | The <scene name='10/1075246/4eb0_with_colored_ligand_stick/1'>substrate-binding site</scene> of LCC is a long, mainly hydrophobic groove that accommodates PET chains. This groove includes three subsites—designated −2, −1, and +1—that interact with specific PET units near the scissile ester bond. Hydrophobic residues such as F125, V212, M166, and F243 line the groove and facilitate binding by interacting with the aromatic rings of the PET molecule. These interactions help align the substrate in the correct position for catalysis. | ||
[[Image:Final rayed image of binding pocket.png|400 px|right|thumb|Figure 2: Ser, His, Asp Catalytic Triad]] | [[Image:Final rayed image of binding pocket.png|400 px|right|thumb|Figure 2: Ser, His, Asp Catalytic Triad]] | ||
