{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Catalase (CAT) is a central antioxidant enzyme that decomposes hydrogen peroxide into water and oxygen, thereby protecting cells from oxidative damage. In human studies, reduced epidermal CAT activity has been implicated in disorders such as vitiligo, where insufficient clearance of H₂O₂ may contribute to melanocyte dysfunction ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "]. In parallel, genetic polymorphisms in the CAT gene appear to influence metabolic parameters and bone health, suggesting that even subtle changes in catalase function may have systemic consequences ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "]. In inflammatory settings, nitric oxide was found to inhibit the proper maturation of catalase—by impairing heme insertion and oligomer formation—which may exacerbate oxidative injury as seen in models of allergic asthma ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "]."}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In animal models of environmental toxicant exposure, such as chronic arsenic ingestion, elevated CAT activity serves as an early biomarker for oxidative stress and associated genetic damage ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "]. Similarly, in diabetic models, diminished catalase activity in kidney and liver tissues is associated with increased oxidative damage, whereas antioxidant interventions (for example, astaxanthin or melatonin) help restore CAT activity and ameliorate tissue injury ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In plants, catalase is equally essential for mitigating oxidative stress under diverse adverse conditions. Under salinity stress, for instance, CAT activity increases at moderate salt levels to reduce H₂O₂ accumulation, although this response may be overwhelmed at high salinity ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "]. In tomato plants challenged with oxidizing residues, elevated catalase activity along with other antioxidant enzymes helps lower H₂O₂ and lipid peroxidation levels, thereby protecting photosynthetic tissues ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": "]. Moreover, under heavy‐metal stress (such as Zn, Fe, or Cu exposure in mandarin, Withania, and maize), modulation of CAT activity forms part of an integrated defense response aimed at maintaining cellular redox homeostasis ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "9", "end_ref": "11"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its role as an oxidative “scavenger,” catalase contributes to maintaining proper cellular function in photosynthetic tissues. In chloroplast preparations, the addition of exogenous catalase has been shown to lessen photoinactivation by eliminating H₂O₂ generated during high‐light stress ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "12"}]}, {"type": "t", "text": "]. Furthermore, studies in barley mutants deficient in catalase underscore its importance in photorespiration, as the lack of CAT leads to aberrant H₂O₂ accumulation and defective carbon metabolism ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "13"}]}, {"type": "t", "text": "]. During leaf senescence, progressive declines in CAT activity are associated with increased oxidative damage, highlighting its role in the aging process ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "14"}]}, {"type": "t", "text": "]. In addition, catalase localized within peroxisomes or glyoxysomes acts not only as a detoxifier but also as an important marker of these organelles in both nodules and developing seeds ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "15"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, in crop species such as barley, wheat, and sorghum, catalase activity is a key component of the antioxidant defence system that responds to stresses including salinity, drought, and combined abiotic challenges. Enhanced CAT activity in these systems—often modulated by treatments such as salicylic acid or through genetic manipulation—correlates with improved stress tolerance and overall plant performance ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "17", "end_ref": "20"}]}, {"type": "t", "text": "]. \n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In summary, across a broad spectrum of biological systems, catalase performs the vital function of detoxifying hydrogen peroxide, thereby protecting cellular structures from oxidative damage. Its expression, maturation, and regulation are finely tuned in response to genetic, environmental, and metabolic cues, making it an indispensable component of both human and plant antioxidative defence mechanisms.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Courtney B Casp, Jin-Xiong She, Wayne T McCormack "}, {"type": "b", "children": [{"type": "t", "text": "Genetic association of the catalase gene (CAT) with vitiligo susceptibility."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Pigment Cell Res (2002)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1034/j.1600-0749.2002.00057.x"}], "href": "https://doi.org/10.1034/j.1600-0749.2002.00057.x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "11837458"}], "href": "https://pubmed.ncbi.nlm.nih.gov/11837458"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Márta Vitai, Krisztina Kocsordi, Barbara Buday, et al. "}, {"type": "b", "children": [{"type": "t", "text": "[Effects of catalase gene (RS769217) polymorphism on energy homeostasis and bone status are gender specific]."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Orv Hetil (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1556/OH.2010.28893"}], "href": "https://doi.org/10.1556/OH.2010.28893"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20494887"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20494887"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Ritu Chakravarti, Karishma Gupta, Alana Majors, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Novel insights in mammalian catalase heme maturation: effect of NO and thioredoxin-1."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Free Radic Biol Med (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.freeradbiomed.2015.01.030"}], "href": "https://doi.org/10.1016/j.freeradbiomed.2015.01.030"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25659933"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25659933"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Mayukh Banerjee, Nilanjana Banerjee, Pritha Ghosh, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Evaluation of the serum catalase and myeloperoxidase activities in chronic arsenic-exposed individuals and concomitant cytogenetic damage."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Toxicol Appl Pharmacol (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.taap.2010.08.013"}], "href": "https://doi.org/10.1016/j.taap.2010.08.013"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20732340"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20732340"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Assaâd Sila, Zohra Ghlissi, Zeineb Kamoun, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Astaxanthin from shrimp by-products ameliorates nephropathy in diabetic rats."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Eur J Nutr (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s00394-014-0711-2"}], "href": "https://doi.org/10.1007/s00394-014-0711-2"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24821271"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24821271"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "A A Agarkov, T N Popova, L V Matasova "}, {"type": "b", "children": [{"type": "t", "text": "[Effect of melatonin on antioxidant state under type ii diabetes at rat]."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biomed Khim (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.18097/pbmc20135904434"}], "href": "https://doi.org/10.18097/pbmc20135904434"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24502141"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24502141"}]}, {"type": "r", "ref": 7, "children": [{"type": "t", "text": "Chengjian Huang, Gang Wei, Yucheng Jie, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Effects of concentrations of sodium chloride on photosynthesis, antioxidative enzymes, growth and fiber yield of hybrid ramie."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Plant Physiol Biochem (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.plaphy.2013.12.021"}], "href": "https://doi.org/10.1016/j.plaphy.2013.12.021"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24486583"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24486583"}]}, {"type": "r", "ref": 8, "children": [{"type": "t", "text": "Mercedes García-Sánchez, José Manuel Palma, Juan Antonio Ocampo, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Arbuscular mycorrhizal fungi alleviate oxidative stress induced by ADOR and enhance antioxidant responses of tomato plants."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Plant Physiol (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.jplph.2013.10.023"}], "href": "https://doi.org/10.1016/j.jplph.2013.10.023"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24594394"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24594394"}]}, {"type": "r", "ref": 9, "children": [{"type": "t", "text": "Pratap Subba, Mainaak Mukhopadhyay, Suresh Kumar Mahato, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Zinc stress induces physiological, ultra-structural and biochemical changes in mandarin orange (Citrus reticulata Blanco) seedlings."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Physiol Mol Biol Plants (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s12298-014-0254-2"}], "href": "https://doi.org/10.1007/s12298-014-0254-2"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25320469"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25320469"}]}, {"type": "r", "ref": 10, "children": [{"type": "t", "text": "Jyoti Ranjan Rout, Sadhana Behera, Nitin Keshari, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Effect of iron stress on Withania somnifera L.: antioxidant enzyme response and nutrient elemental uptake of in vitro grown plants."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Ecotoxicology (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s10646-014-1389-1"}], "href": "https://doi.org/10.1007/s10646-014-1389-1"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25480472"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25480472"}]}, {"type": "r", "ref": 11, "children": [{"type": "t", "text": "Jyoti R Rout, Shidharth S Ram, Ritarani Das, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Copper-stress induced alterations in protein profile and antioxidant enzymes activities in the in vitro grown Withania somnifera L."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Physiol Mol Biol Plants (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s12298-013-0167-5"}], "href": "https://doi.org/10.1007/s12298-013-0167-5"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24431504"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24431504"}]}, {"type": "r", "ref": 12, "children": [{"type": "t", "text": "B Barényi, G H Krause "}, {"type": "b", "children": [{"type": "t", "text": "Inhibition of photosynthetic reactions by light : A study with isolated spinach chloroplasts."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Planta (1985)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/BF00393510"}], "href": "https://doi.org/10.1007/BF00393510"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24249342"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24249342"}]}, {"type": "r", "ref": 13, "children": [{"type": "t", "text": "A C Kendall, A J Keys, J C Turner, et al. "}, {"type": "b", "children": [{"type": "t", "text": "The isolation and characterisation of a catalase-deficient mutant of barley (Hordeum vulgare L.)."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Planta (1983)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/BF00409139"}], "href": "https://doi.org/10.1007/BF00409139"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24258326"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24258326"}]}, {"type": "r", "ref": 14, "children": [{"type": "t", "text": "M Kar, J Feierabend "}, {"type": "b", "children": [{"type": "t", "text": "Metabolism of activated oxygen in detached wheat and rye leaves and its relevance to the initiation of senescence."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Planta (1984)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/BF00429753"}], "href": "https://doi.org/10.1007/BF00429753"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24258664"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24258664"}]}, {"type": "r", "ref": 15, "children": [{"type": "t", "text": "A Puppo, L Dimitrijevic, J Rigaud "}, {"type": "b", "children": [{"type": "t", "text": "Possible involvement of nodule superoxide dismutase and catalase in leghemoglobin protection."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Planta (1982)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/BF00397477"}], "href": "https://doi.org/10.1007/BF00397477"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24272584"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24272584"}]}, {"type": "r", "ref": 16, "children": [{"type": "t", "text": "T K Fang, R P Donaldson, E L Vigil "}, {"type": "b", "children": [{"type": "t", "text": "Electron transport in purified glyoxysomal membranes from castor-bean endosperm."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Planta (1987)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/BF00403023"}], "href": "https://doi.org/10.1007/BF00403023"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24225782"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24225782"}]}, {"type": "r", "ref": 17, "children": [{"type": "t", "text": "Aslihan Temel, Nermin Gozukirmizi "}, {"type": "b", "children": [{"type": "t", "text": "Physiological and molecular changes in barley and wheat under salinity."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Appl Biochem Biotechnol (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s12010-014-1464-3"}], "href": "https://doi.org/10.1007/s12010-014-1464-3"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25578157"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25578157"}]}, {"type": "r", "ref": 18, "children": [{"type": "t", "text": "Mengesha T Dugasa, Fangbin Cao, Wasim Ibrahim, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Differences in physiological and biochemical characteristics in response to single and combined drought and salinity stresses between wheat genotypes differing in salt tolerance."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Physiol Plant (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/ppl.12743"}], "href": "https://doi.org/10.1111/ppl.12743"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "29635753"}], "href": "https://pubmed.ncbi.nlm.nih.gov/29635753"}]}, {"type": "r", "ref": 19, "children": [{"type": "t", "text": "Hülya Torun "}, {"type": "b", "children": [{"type": "t", "text": "Time-course analysis of salicylic acid effects on ROS regulation and antioxidant defense in roots of hulled and hulless barley under combined stress of drought, heat and salinity."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Physiol Plant (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/ppl.12798"}], "href": "https://doi.org/10.1111/ppl.12798"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "29984429"}], "href": "https://pubmed.ncbi.nlm.nih.gov/29984429"}]}, {"type": "r", "ref": 20, "children": [{"type": "t", "text": "P Surender Reddy, Gadi Jogeswar, Girish K Rasineni, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Proline over-accumulation alleviates salt stress and protects photosynthetic and antioxidant enzyme activities in transgenic sorghum [Sorghum bicolor (L.) Moench]."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Plant Physiol Biochem (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.plaphy.2015.05.014"}], "href": "https://doi.org/10.1016/j.plaphy.2015.05.014"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26065619"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26065619"}]}]}]}