ЕС 4.2.1.1

Carbonic anhydrase from human erythrocytes (HCA) has been used to study the molten-globule state of carbonic anhydrase (CA). Chaperone-like α-crystallin binds to this state of the enzyme and prevents its aggregation. The enzyme from sigma has been used for the analysis of thermodynamic stability of the enzyme. Furthermore, its clinical significance has been evaluated in human non-small cell lung cancer.

Carbonic Anhydrase is a metalloenzyme?with zinc. The active site of carbonic anhydrase contains three conserved histidine residues (His94, His96 and His119).

Purify carbonic anhydrase by hydroxylapatite and DEAE-cellulose chromatography [Tiselius et al. Arch Biochem Biophys 65 132 1956, Biochim Biophys Acta 39 218 1960], and is then dialysed for crystallisation. A 0.5 to 1% solution of the enzyme in 0.05 M Tris-HCl pH 8.5 is dialysed against 1.75M solution of (NH4)2SO4 in the same buffer, and this solution is slowly increased in salt concentration by periodic removal of small amounts of dialysate and replacing with an equal volume of 3.5M (NH4)2SO4. The final salt concentration, in which the DEAE-cellulose fractions give beautiful birefringent suspensions of crystals, ranged from 2.4 to 2.7M and appeared first as fine crystals, then underwent transition to thin fragile plates. Carbonic anhydrase is a Zn enzyme which exists as several isoenzymes of varying degrees of activity [J Biol Chem 243 6474 1968, crystal structure: Nature, New Biology 235 131 1972; see also P.D. Boyer Ed. The Enzymes Academic Press NY, pp 587-665 1971].