Phospholipase A2
The enzyme phospholipase A2 (EC 3.1.1.4, PLA2, systematic name phosphatidylcholine 2-acylhydrolase) catalyse 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
| 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 | ||||||||
| |||||||||
| 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 | ||||||||
| |||||||||
This particular phospholipase specifically recognizes the sn2 acyl bond of phospholipids and catalytically hydrolyzes the bond, releasing arachidonic acid and 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.