Catalase (bacterial hydrogen peroxide scavenging enzyme systems)

Bacteria produce a group of enzymes—including catalase, catalase-peroxidase, alkyl hydroperoxide reductase (AhpC), and glutathione peroxidase—to scavenge and detoxify hydrogen peroxide (H₂O₂), a reactive oxygen species that is toxic to cells and generated both by aerobic metabolism and host immune defenses[1][2][4][8]. These enzyme systems protect bacteria from oxidative damage to DNA, proteins, and lipids, enabling survival in oxygenated environments and during immune attack[1][2][6]. Different bacteria possess distinct combinations of these enzymes, with catalase and peroxidases being primary defense mechanisms[1][4]. Genetic or functional disruption of these systems increases bacterial susceptibility to oxidative stress and reduces virulence[1]. Catalase activity is widely used as a biomarker for bacterial identification and classification[2][8]. Antibiotics and host defenses may act, in part, by overwhelming or circumventing these protective enzyme systems[5]. This entry is non-standard because it refers to a *system* or *pathway*—not a single, canonical molecular entity or protein—but rather a collection of related enzymes with overlapping functions, sometimes collectively called "ROS-scavenging enzymes" or "bacterial catalases/peroxidases"[1][4][6]. Notes regarding is_incorrect: - The target as named, "Bacterial protein/enzyme systems via hydrogen peroxide generation," is too broad and not the standard canonical name for a specific molecular target. - The accurate target would be an individual enzyme such as "Catalase (katA)", "Alkyl hydroperoxide reductase (AhpC)", or "Catalase-peroxidase (katG)". - The entry as written groups together multiple proteins/enzymes under a functional description rather than a unique, properly-named molecular entity. For most structured databases, these would be mapped to their individual, well-characterized enzyme names.

Other names

CatalaseCatalase-peroxidaseNADH peroxidaseAlkyl hydroperoxide reductaseAhpCGlutathione peroxidaseThiol peroxidaseMn-catalasePeroxidase enzymes

Enzymatic decomposition of hydrogen peroxide to water and oxygen, Peroxidase-mediated reduction of hydroperoxides, Protection against host reactive oxygen species as an immune evasion strategy