title: Purification, stability and kinetic properties of highly purified adenosine deaminase from Bacillus cereus NCIB 8122.
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.
mesh_terms: D000243:Adenosine Deaminase / Q000302:isolation & purification* / Q000378:metabolism; D001409:Bacillus cereus / Q000201:enzymology*; D002414:Cations, Monovalent; D004795:Enzyme Stability; D005990:Glycerol / Q000494:pharmacology; D007700:Kinetics; D009700:Nucleoside Deaminases / Q000302:isolation & purification*
chemical_list: D002414:Cations, Monovalent; D009700:Nucleoside Deaminases; D000243:Adenosine Deaminase; D005990:Glycerol