Purification and properties of Serratia marcescens purine nucleoside phosphorylase

摘要

Serratia marcescens purine nucleoside phosphorylase (PNP) was purified to homogeneity by streptomycin sulfate treatment, Sephacryl HR S-200 gel filtration chromatography and AMP-agarose affinity chromatography. The specific activity of the enzyme was increased 49-fold during purification with an overall yield of 7.0 percent. The molecular weight was 168 kD as estimated by Sephadex G-150 gel filtration chromatography. The S. marcescens enzyme was composed of six identical subunits with subunit molecular weight of 28 kD, as estimated by SDS-PAGE. The Km values of S. marcescens enzyme for inosine and deoxyinosine were 0.38 and 1.20 mM, respectively. The pH optimum was near 8.0, and the enzyme was relatively heat-stable protein. The enzyme was inactivated completely by 0.5 mM of Cu~(2+).