Carbonic Anhydrase
Masahiko Mori in Histochemistry of the Salivary Glands, 2019
Carbonic anhydrase (CA) catalyzes the interconversion of carbon dioxide and bicarbonate; the reaction is thought to regulate cellular activity regarding CO2 exchange, secretion of ions, calcification, and pH balances. CA is widely distributed in several mammalian tissues as revealed by biochemical and histochemical studies. The biochemical significances of CA in salivary glands include the membrane transport of CO2 ions into saliva1,2 and the participation in glandular secretions.3–5 The isoenzymes of CA in mammalian cells have been separated and designated CA I, CA II, and CA III. CA I and CA II have molecular weights of about 30,000. CA I has low and CA II has high activity. Fine et al.6 stated that CA I and CA II exhibit no cross activity; however, immunosera against human CA I, human CA II, and bovine CA II showed cross reaction to other mammalian species. The first histochemical detection of CA used the cobalt-bicarbonate technique.7 A modification of the cobalt-bicarbonate method of Häussier8 and Hansson9 uses floating sections; however, these methods occasionally develop artifacts.10 Other immunohistochemical methods for detecting CA and isoenzymes have used immunofluorescein-labeled antibody and peroxidase immunoglobulin methods. Many tissues and organs in mammals including man contain CA isoenzymes with varying intensities.3,5,11,12
New Biological Targets for the Treatment of Leishmaniasis
Venkatesan Jayaprakash, Daniele Castagnolo, Yusuf Özkay in Medicinal Chemistry of Neglected and Tropical Diseases, 2019
Carbonic anhydrases (CAs, EC 4.2.1.1) belong to a superfamily of metalloenzymes which are present through most living organisms. They are encoded by seven evolutionarily unrelated gene families and are classified using the Greek letters α-, β-, γ-, δ-, ζ- ɳ- and θ- (Supuran 2017). All these enzymes reversibly catalyze the hydration of carbon dioxide (CO2 + H2 ⇆ HCO3− + H+) by means of a ‘ping-pong mechanism’ as highlighted in Figure 6, which reports as a model the catalytic pathway for the ubiquitous human (h) CA II isoform (Supuran 2008). Catalytic mechanism of CO2 hydration.
Medical Therapy for Glaucoma
Neil T. Choplin, Carlo E. Traverso in Atlas of Glaucoma, 2014
Carbonic anhydrase is an enzyme found predominantly in the ciliary epithelium, the kidney, the central nervous system, and the red blood cells. It catalyzes the combination of water and carbon dioxide to form bicarbonate and hydrogen ions. Within the ciliary epithelium, hydrogen ions are exchanged for sodium ions, some bicarbonate is exchanged for chloride, and bicarbonate and/or chloride are actively transported into the aqueous with sodium and water passively following. The enzyme carbonic anhydrase must be inhibited at least 99% in order to decrease aqueous formation. This degree of inhibition results in reductions in aqueous humor formation of up to 30% with maximum doses of oral carbonic anhydrase inhibitors (CAI) and up to 19% with maximum doses of topical CAIs.
Anion inhibition studies of a beta carbonic anhydrase from the malaria mosquito Anopheles gambiae
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Daniela Vullo, Leo Syrjänen, Marianne Kuuslahti, Seppo Parkkila, Claudiu T. Supuran
Carbonic anhydrases (CAs, EC 4.2.1.1) are enzymes that catalyse the reversible hydration reaction of carbon dioxide according to the following reaction2: CO2 + H2O ↔ HCO3− + H+. CAs are typically zinc-containing metalloenzymes, but the ζ form uses cadmium or zinc (in an inter-exchangeable manner), as an alternative metal cofactor3,4. In addition, γ-CAs may contain iron(II) within the active site, at least in some anaerobic Archaea5,6. The reaction catalysed by CAs is crucial in the regulation of acid–base balance in organisms. Additionally, this reaction participates in removing carbon dioxide out of tissues, takes part in biosynthetic reactions such as gluconeogenesis and ureagenesis, and is involved in many other physiological processes as well2. Seven classes of carbonic anhydrases have been identified: the α, β, γ, δ, ζ, η and θ-CAs7. Of these, β-CAs appear to be the family with the widest distribution7. They have been described from various groups of organisms including the Bacteria and Archaea domains as well as in all species of plants and some fungi among Eukarya8. In addition, our previous studies suggested the widespread occurrence of at least one single-copy of a β-CA gene among animal species distinct from chordates9.
Carbonic anhydrase I–II autoantibodies and oxidative status in long-term follow-up of patients with Crimean–Congo haemorrhagic fever
Published in Archives of Physiology and Biochemistry, 2018
Hülya Yilmaz, Uğur Kostakoğlu, Selim Demir, Firdevs Aksoy, Ahmet Menteşe, Süleyman Caner Karahan, İftihar Köksal, Ahmet Alver, Gürdal Yilmaz
Carbonic anhydrase (CA; EC 4.2.1.1) is a zinc enzyme responsible for the catalysation of reversible hydration of CO2. There are 16 known CA isoenzymes in mammals. These differ in terms of tissue distributions and cellular positions. These isozymes are involved in such physiological processes as including CO2 transport, ion secretion, pH regulation, and calcification (Supuran 2008). CA autoantibodies have recently been reported in a number of autoimmune or idiopathic diseases and in carcinomas. However, the mechanisms behind the immune response in question are still unclear (Alver et al. 2007; Adamus 2009; Aydin et al. 2013). The purpose of this study was to measure oxidative stress and carbonic anhydrase autoantibody levels in patients with conformed diagnosis of CCHF and to compare the results with those of healthy controls in our community.
Synthesis of novel tris-chalcones and determination of their inhibition profiles against some metabolic enzymes
Published in Archives of Physiology and Biochemistry, 2021
Serdar Burmaoglu, Ali Osman Yilmaz, M. Fatih Polat, Rüya Kaya, İlhami Gulcin, Oztekin Algul
Carbonic anhydrase (CA, E.C. 4.2.1.1) plays an important role in the acid–base balance and supplies an essential buffering system for fluids in the body and tissues (Topal et al.2017, Tugrak et al.2018). This enzyme family catalyses a very simple reversible conversion of carbon dioxide (CO2), which is produced by metabolic processes, and water to bicarbonate (HCO3–), which is transported in the blood to organs and tissues, and protons (H+). Kidneys and lungs are the crucial organs in the buffering systems. In the lungs, bicarbonate is converted to CO2, which is eliminated through breathing processes. There is a fine balance between HCO3− and H+ in the body fluids. This balance is established by the elimination of excessive H+ and re-absorption of HCO3− from the kidneys (Zengin et al.2018, Biçer et al. 2019).
Related Knowledge Centers
- Active Site
- Bicarbonate
- Carbon Dioxide
- Carbonic Acid
- Catalysis
- Enzyme
- Metalloprotein
- Dissociation
- Zinc
- Acid–Base Homeostasis