*7.2. GPx*

GPx is usually in the mitochondria and cytosol of various cells and is mainly a glycoprotein containing selenocysteine residues. This antioxidant enzyme is skilled in converting H2O2 to water. This enzyme also participates in the catalysis cycle to reduce hydroperoxides to alcohol and ultimately involves the oxidation of GSSG induced by GSH [97]. There is a positive relationship between increased GPX concentration and anti-inflammatory activity of the cardiovascular system. On the other hand, lipid hydroperoxides such as cholesterol, free fatty acids, cholesterol esters, and phospholipids are rapidly neutralized by phospholipases and GPX. It is also noteworthy that the detoxification of lipid hydroperoxides is performed by the enzymes PRx, glutathione S-transferase (GST), and GPX [92]. To date, approximately five different isoforms of GPX have been identified. These isoforms include cytosolic or classical GPX (cGPX or GPx1), gastrointestinal GPX (GIGPX or GPX2), plasma GPX (PGPX or GPX3), phospholipid GPX (PHGPX or GPX4), and sperm nuclear GPx or GPx (Sn) [97].
