DOPA decarboxylase: Difference between revisions
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====Step 3: Formation of a Quinonoid Intermediate==== | ====Step 3: Formation of a Quinonoid Intermediate==== | ||
The formation of the quinonoid intermediate is common to all PLP-dependent enzymes, yet the orientation of the intermediate, as determined by key residues of the enzyme active site, determines the subsequent reaction (for example whether it will be a decarboxylation or transamination). A salt bridge that exists between Asp271 and the protonated pyridine nitrogen of PLP further enhances the ability of PLP to act as an electron sink and promote catalysis. As well, During the formation of the quinonoid intermediate, carbon dioxide is released. | The formation of the quinonoid intermediate is common to all PLP-dependent enzymes, yet the orientation of the intermediate, as determined by key residues of the enzyme active site, determines the subsequent reaction (for example whether it will be a decarboxylation or transamination). A salt bridge that exists between Asp271 and the protonated pyridine nitrogen of PLP further enhances the ability of PLP to act as an electron sink and promote catalysis. As well, During the formation of the quinonoid intermediate, carbon dioxide is released. | ||
====Step 4: Formation of an External Aldimine==== | |||
The formation of the external aldimine between the product and PLP is the fourth step of the reaction. Here, Tyr332, with the assistance of His192, likely donates a proton to the quinonoid Cα intermediate. | The formation of the external aldimine between the product and PLP is the fourth step of the reaction. Here, Tyr332, with the assistance of His192, likely donates a proton to the quinonoid Cα intermediate. | ||
====Step 5: Formation of an Internal Aldimine and Product Release==== | ====Step 5: Formation of an Internal Aldimine and Product Release==== | ||
