- A purification protocol that encompassed anion exchange chromatography (EC) on DEAE-cellulose, cation EC on CM-cellulose, anion EC on Q-Sepharose, and fast protein liquid chromatography-gel filtration of Superdex 75 was used to isolate a ribonuclease from dried fruiting bodies of Ramaria formosa. The ribonuclease was unadsorbed on CM-cellulose but adsorbed on both DEAE-cellulose and Q-Sepharose. It displayed a molecular mass of 29-kDa in both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The ranking of its ribonucleolytic activity toward polyhomoribonucleotides was poly(U) > poly(C) > poly(G) > poly(A). It exhibited a pH optimum of pH 5 and a temperature optimum at 60 °C. The ribonuclease inhibited HIV-1 reverse transcriptase with an IC50 of 3 µM. |