Purification, stability and kinetic properties of highly purified adenosine deaminase from Bacillus cereus NCIB 8122.
BIOCHIMICA ET BIOPHYSICA ACTA 1986;
884:490-6. [PMID:
3096380 DOI:
10.1016/0304-4165(86)90199-6]
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Abstract
Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) from Bacillus cereus NCIB 8122 has been purified to electrophoretic homogeneity by ammonium sulfate precipitation, gel filtration through Sephadex G-100, DEAE-Sephadex A-50 chromatography and ion-exchange HPLC on DEAE-Polyol. The enzyme activity is stabilized (at temperatures from 0 degrees C to 40 degrees C) by 50 mM NH4+ or K+, while it is irreversibly lost in the absence of these or a few other monovalent cations. Glycerol (24% by volume) helps the cation in stabilizing the enzyme activity above 40 degrees C, but also exerts per se a noticeable protecting effect at room temperature. B. cereus adenosine deaminase displays the following properties: Mr on Sephadex G-200, 68,000; Mr in SDS-polyacrylamide gel electrophoresis, 53,700; optimal pH-stability (in the presence of 50 mM KCl) over the range 8-11 at 4 degrees C, and maximal catalytic activity at 30 degrees C between pH 7 and 10; Km for adenosine around 50 microM over the same pH range and Km for 2'-deoxyadenosine around 400 microM.
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