phosphatidylserine decarboxylase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: H+ + phosphatidyl-L-serine = CO2 + phosphatidylethanolamine. [EC:4.1.1.65, RHEA:20828]

Phosphatidylserine decarboxylase activity is a crucial enzymatic process involved in the biosynthesis of phosphatidylethanolamine (PE), a major phospholipid component of cell membranes. This activity is catalyzed by the enzyme phosphatidylserine decarboxylase (PSD), which removes the carboxyl group from the head group of phosphatidylserine (PS) to generate PE. The reaction occurs at the cytosolic leaflet of the endoplasmic reticulum (ER) membrane and is essential for maintaining the proper composition and function of cellular membranes. PSD is a highly conserved enzyme present in all eukaryotes and some bacteria.

The molecular function of PSD activity involves the following steps:

1. **Substrate Binding:** PSD specifically binds to PS as a substrate. PS has a serine head group with a carboxyl group attached.
2. **Decarboxylation:** PSD catalyzes the removal of the carboxyl group from the serine head group of PS. This reaction involves the transfer of a proton from a lysine residue in the enzyme's active site to the carboxyl group, forming a carboxylate anion. The carboxylate anion then undergoes decarboxylation, releasing carbon dioxide (CO2) as a byproduct.
3. **Product Formation:** The decarboxylation reaction results in the formation of PE, which has an ethanolamine head group. PE is a critical component of cell membranes, playing a role in membrane fluidity, lipid signaling, and protein interactions.

The precise mechanism of decarboxylation by PSD involves the formation of a transient carbamate intermediate, where the carboxylate anion is covalently linked to the active site lysine residue. This intermediate facilitates the release of CO2 and the formation of PE.

In summary, phosphatidylserine decarboxylase activity is a crucial enzyme activity responsible for the synthesis of PE from PS. This activity is essential for maintaining the integrity and function of cell membranes and is regulated by factors such as substrate availability, enzyme activity, and cellular demand for PE. The molecular function of PSD involves substrate binding, decarboxylation, and product formation, with the enzyme utilizing a specific mechanism to catalyze the removal of the carboxyl group from PS.'
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Proteins (1)

Compounds (6)