Phospholipase A2
| phospholipase A2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Phospholipase cleavage sites. Note that an enzyme that displays both PLA1 and PLA2 activities is called a phospholipase B. | |||||||||
| Identifiers | |||||||||
| EC no. | 3.1.1.4 | ||||||||
| CAS no. | 9001-84-7 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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| Phospholipase A2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Bee venom phospholipase A2 sPLA2. Middle plane of the lipid bilayer - black dots. Boundary of the hydrocarbon core region - red dots (extracellular side). Layer of lipid phosphates - yellow dots. | |||||||||
| Identifiers | |||||||||
| Symbol | Phospholip_A2_1 | ||||||||
| Pfam | PF00068 | ||||||||
| InterPro | IPR001211 | ||||||||
| PROSITE | PDOC00109 | ||||||||
| SCOP2 | 1bbc / SCOPe / SUPFAM | ||||||||
| OPM superfamily | 82 | ||||||||
| OPM protein | 1g4i | ||||||||
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The enzyme phospholipase A2 (EC 3.1.1.4, PLA2, systematic name phosphatidylcholine 2-acylhydrolase) catalyses the cleavage of fatty acids in position 2 of phospholipids, hydrolyzing the bond between the second fatty acid "tail" and the glycerol molecule:
- phosphatidylcholine + H2O = 1-acylglycerophosphocholine + a carboxylate
This particular phospholipase specifically recognizes the sn2 acyl bond of phospholipids and catalytically hydrolyzes the bond, releasing arachidonic acid and lysophosphatidyl choline, a precursor of lysophosphatidic acid. Upon downstream modification by cyclooxygenases or lipoxygenases, arachidonic acid is modified into active compounds called eicosanoids. Eicosanoids include prostaglandins and leukotrienes, which are categorized as anti-inflammatory and inflammatory mediators.
PLA2 enzymes are commonly found in mammalian tissues as well as arachnid, insect, and snake venom. Venom from bees is largely composed of melittin, which is a stimulant of PLA2. Due to the increased presence and activity of PLA2 resulting from a snake or insect bite, arachidonic acid is released from the phospholipid membrane disproportionately. As a result, inflammation and pain occur at the site. There are also prokaryotic A2 phospholipases.
Additional types of phospholipases include phospholipase A1, phospholipase B, phospholipase C, and phospholipase D.