کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1948478 | 1054696 | 2007 | 8 صفحه PDF | دانلود رایگان |
Adenosine phosphorylase, a purine nucleoside phosphorylase endowed with high specificity for adenine nucleosides, was purified 117-fold from vegetative forms of Bacillus cereus. The purification procedure included ammonium sulphate fractionation, pH 4 treatment, ion exchange chromatography on DEAE-Sephacel, gel filtration on Sephacryl S-300 HR and affinity chromatography on N6-adenosyl agarose. The enzyme shows a good stability to both temperature and pH. It appears to be a homohexamer of 164 ± 5 kDa. Kinetic characterization confirmed the specificity of this phosphorylase for 6-aminopurine nucleosides. Adenosine was the preferred substrate for nucleoside phosphorolysis (kcat/Km 2.1 × 106 s− 1 M− 1), followed by 2′-deoxyadenosine (kcat/Km 4.2 × 105 s− 1 M− 1). Apparently, the low specificity of adenosine phosphorylase towards 6-oxopurine nucleosides is due to a slow catalytic rate rather than to poor substrate binding.
Journal: Biochimica et Biophysica Acta (BBA) - General Subjects - Volume 1770, Issue 10, October 2007, Pages 1498–1505