Classification of Carbonic Anhydrases

There are several types of -class CAs i.e., a-CA I-VII, reported in the literature, out of which the human carbonic anhydrase II (HCA II), the most extensively studied carbonic anhydrase, has an exceptionally high CO2 hydration rate and a wide tissue distribution 107). The HCA II comprises a single polypeptide chain with a molecular mass of 29.3 kDa and contains one catalytic zinc ion, coordinated to three histidine residues, His 94, His 96, and His 119. A tetrahedral coordination geometry around the metal center is completed with a water molecule, which forms a hydroxide ion with a pK value of 7.0 108). Quigley and co-workers 109,110) reported that the inhibition of the synthesis of HCO3 from CO2 and OH- reduces aqueous humor formation and lowers intra-ocular pressure, which is a major risk factor for primary open-angle glaucoma. 

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B. Aquation/Decarboxylation Reaction Discovery and Classification of Carbonic Anhydrases... 

Diuretics John P Howe Introduction Classification Osmotic diuretics Carbonic anhydrase inhibitors Loop diuretics inhibitors of Na+/K+/2CI- transport Thiazide diuretics... 

The aqueous suppressants include the P-adrenergic antagonists, a-agonists, carbonic anhydrase inhibitors (CAIs topical and oral), and hyperosmotics (intravenous). The topical fiarms of this classification are used routinely in clinical practice. The oral and intravenous formulations are generally reserved fiar use under special circumstances. 

Reflecting the lack of in-depth experimental data available at this time, even the classiflcation of metal-dependent enzymes was notably nonsystematic. In an early review, five categories were set forth heme, copper-containing, proteolytic, carbonic anhydrase, and phosphatase . A later classification" was made according to the types of reactions catalyzed electron transfer or redox (Cu, Fe, Mo), group transfer (Mg, Mn), decarboxylations and hydrolyses (Mn, Zn), and binding of pyridine nucleotide cofactors (Zn). 

Classification of inhibitors of bovine carbonic anhydrase II according to the electronic spectral properties of the adducts with cobalt(ll) derivatives. ... 

Carbonic anhydrases, also known as carbonate dehydratase and placed in enzyme classification 4.2.1.1, are zinc metalloproteins that catalyze the reversible hydration of carbon dioxide to bicarbonate (Eq. 1) ... 

Carbohydrates, Recognition of, p. 169 Carbonic Anhydrase Models, p. 178 Carcerands and Hernicarcerands. p. 189 Cation-n Interactions, p. 214 Cavitands, p. 219 Chiral Guest Recognition, p. 236 Classical Descriptions of Inclusion Compounds, p. 253 Classification and Nomenclature of Supramolecular Compounds, p. 261 Clathrate Hydrates, p. 274 Conzplexation of Fullerenes, p. 302 Concepts in Ciystal Engineering, p. 319 Crown Ethers, p. 326 Cryptands, p. 334 Cryptophanes, p. 340 Cyclodextrins, p. 398... 

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