Preparation and characterization of 5′-phosphodiesterase from barley malt rootlets

摘要

Two 5′- phosphodiesterases (5′-PDE-a and 5′-PDE-b) were isolated from barley malt rootlets, and further purified by gel filtration on Sephadex G-25 and Sephadex G-75. 5′-PDE-a had a pH optimum of 5.0, temperature optimum of 70°C, and specific activity of 0.0143 mM·mg~(-1)·min~(-1). 5′-PDE -b had a pH optimum of 6.0, temperature optimum of 65°C and specific activity of 0.0125 mM·mg~(-1)·min~(-1). Both enzymes can be used to hydrolyze RNA to form 5′-nucleotides. The enzymes were quite stable at 70°C for 420 minutes. The K_m was 0.24 mM for 5′-PDE-a and 0.16 mM for 5′-PDE-b with t-RNA (yeast) as substrate.