Phospholipase A2

Phospholipase A2 ( correct: phosphatidylcholine -2- acylhydrase, short PLA2 ) are called enzymes that cleave fatty acids from C2 atom of phosphoglycerides. They are therefore essential for eukaryotes in the degradation of these substances, as well as the initial reaction in the biosynthesis of prostaglandins. In addition, the poison of serpents, Waranartigen, insects, crown of thorns starfish and some molluscs contain these enzymes. Mammals have at least four types PA2, man has 16 isoforms. Mutations in the PLA2G6 gene can lead to rare hereditary neurodegeneration with brain iron accumulation and Karak syndrome.

Classification

The classification of PLA2 occurs after localization in cytosolic and secreted phospholipases A2.

The secreted PLA2 are found predominantly in amniotes, 19 are known from arthropods and two of Cnidaria. Almost all known PLA2 of reptiles are snakes and viper -like, three in Heloderma. All PLA2 of reptiles and arthropods are secreted by the venom gland and act as a toxin and allergen. The distribution of PLA2 in higher mammals into the blood plasma can be done for several reasons, the most important is signaling in the inflammatory response. Some isoforms may be localized in the cell membrane after secretion.

The cytosolic PLA2 have been found only in quadrupeds and in zebrafish, continue in plants and Proteobacteria.

In humans, different isoforms of PLA2 can be localized not only in different cell types, but also be specific for different substrates. Human PLA2 are:

• Secreted: PLA2G1B, PLA2G2A, PLA2G2D, PLA2G2E, PLA2G2F, PLA2G3, PLA2G5, PLA2G10, PLA2G12A
• Cytosol: PLA2G4A, PLA2G4B, PLA2G4C, PLA2G4D, PLA2G4E, PLA2G4F, PLA2G6, PLA2G12A

Catalyzed reaction

The enzyme is from the family of esterases, catalyzes the hydrolysis of phospholipids at the second carbon atom ( β - carbon atom). It is, inter alia, to the release of arachidonic acid from membrane lipids.

Phospholipase A2 can be inhibited by glucocorticoids, which limits the synthesis of eicosanoids, and therefore anti-inflammatory (anti -inflammatory ) effect.

Importance for the occurrence of coronary heart disease

In a study published in the May 2010 study, the authors examined on 79 036 patients, the extent to which the Phosholipase -A2 levels were associated with the risk of occurrence of coronary heart disease, stroke or death case. Here, a clear correlation, which increased Phosholipase -A2 levels in the blood showed a par with the risk presented values ​​of high blood pressure or high LDL - cholesterol levels in the blood.