1-Cysteine peroxiredoxin: A dual-function enzyme with peroxidase and acidic Ca2+-independent phospholipase A2 activities

Peroxiredoxins (Prx) are enzymes that catalyze the reduction of hydrogen peroxide and alkyl hydroperoxides. Prxs are ubiquitous enzymes with representatives found in Bacteria, Archaea and Eukarya. Many 1-cysteine peroxiredoxins (1-CysPrx) are dual-function enzyme with both peroxidase and acidic Ca2+-independent phospholipase A2 (aiPLA2) activities. The functions proposed for 1-CysPrx/aiPLA2 include the protection of cell membrane phospholipids against oxidative damage (peroxidation) and the metabolism (hydrolysis) of phospholipids, such as those of lung surfactant. The peroxidase active site motif PVCTTE of 1-CysPrx contains the conserved catalytic cysteine residue, and the esterase (lipase) motif GXSXG of the enzyme contains the conserved catalytic serine residue. In addition to the classic lipase motif GXSXG, various 1-CysPrx/aiPLA2s have closely related variant putative lipase motifs containing the catalytic serine residue. The PLA2 moieties are prevalent and highly homologous in vertebrate and bacterial 1-CysPrx/aiPLA2s that is consistent with a high degree evolutional conservation of the enzyme.