Description
The carbonic anhydrases (or carbonate dehydratases) form a family of enzymes that catalyze the rapid interconversion of carbon dioxide and water to bicarbonate and protons (or vice versa), a reversible reaction that occurs relatively slowly in the absence of a catalyst. The active site of most carbonic anhydrases contains a zinc ion; they are therefore classified as metalloenzymes.
Abbr
Carbonic Anhydrase, Native (Bovine)
Source
Bovine Erythrocytes
Applications
CO2 determination in blood; Elimination of CO2 in reagents for acidity testing; Carboxy group transfers; Reduction reactions.
Product Overview
It was from Bovine Erythrocytes. A dialyzed, lyophilized powder.
Enzyme Commission Number
EC 4.2.1.1
Activity
> 3,000 units per mg dry weight
Molecular Weight
29.0 kDa (Theoretical) 30 kDa (Lindskog et al. 1971)
Isoelectric point
6.40 (Theoretical)
Composition
Sixteen CA isozymes have been described so far in mammals. Erythrocyte CAs, CA-I and CA-II, are most well known. CA-I, CA-II, CA-III, CA-VII, and CA-XIII are cytosolic. CA-IV, CA-IX, CA-XII, CA-XIV, and CA-XV are membrane bound. CA-VI is secreted in saliva. CA-VA and CA-VB are mitochondrial. There are also three acatalytic forms referred to as CA-related proteins (CARPs): CARP-VIII, CARP-X, and CARP-XI (Coban et al. 2009). The zinc metal is always bound to histidines 93, 95, and 118 (mature chain numbering). A hydrogen bonded network, linked to the zinc-bonded water molecule and these histidines either directly or indirectly, includes 28-Ser, 91-Glu, 105-Glu, 106-His, 116-His, 193-Tyr, 198-Thr, 208-Trp, and 223-Asn. These residues have been found to be highly conserved (Lindskog 1982, and Lindskog et al. 1984). Bovine and human CA I and II contain a unique C-terminal knot structure, which has been shown to be important in enzymatic and mechanical properties (Alam et al. 2002).
Specificity
Blood CO2 transport and excretion is largely dependent on the rapid catalysis of the CO2 reactions within the erythrocyte by CA (Tufts et al. 2003). Bovine CA reversibly hydrates alkyl pyruvates and it exhibits hydratase activity toward a wide variety of substrates (Pocker et al. 1974, and Wells et al. 1975).
Unit Definition
One Unit is determined by the electrometric method of Wilbur and Anderson (J. Biol. Chem., 176, 147 (1948)), in which the time required (in seconds) for a saturated CO2 solution to lower the pH of 0.02M Tris-HCl buffer from 8.3 to 6.3, at 0-4°C is determined.
Optimum pH
7.0-7.5 (Demir et al. 2000, and Tasgin et al. 2009)
Activators
HPO42-(Rowlett et al. 1991); SO32-(Rowlett et al. 1991)
Inhibitors
Monovalent anions (Lindskog et al. 1971, and Ward and Cull 1972); Sulfonates and sulfonamides (Pocker and Watamori 1973, and Binford et al. 1974); Imidazole (Edsall 1968)
Pathway
Bile secretion, organism-specific biosystem; Collecting duct acid secretion, organism-specific biosystem; Metabolism, organism-specific biosystem
Function
carbonate dehydratase activity; zinc ion binding
Synonyms
carbonic anhydrases; carbonate dehydratases; EC 4.2.1.1; anhydrase; carbonate anhydrase; carbonic acid anhydrase; carboxyanhydrase; carbonic anhydrase A; carbonate hydro-lyase
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