A novel ribonuclease with antiproliferative activity toward leukemia and lymphoma cells and HIV-1 reverse transcriptase inhibitory activity from the mushroom, Hohenbuehelia serotina.

In this study, a 27-kDa ribonuclease (RNase) was purified from the dried fruiting bodies of the mushroom, Hohenbuehelia serotina. The isolation protocol involved anion exchange chromatography, affinity chromatography, cation exchange chromatography and gel filtration in succession. The RNase was unadsorbed on DEAE-cellulose, but was adsorbed on Affi-gel blue gel and CM-cellulose. The N-terminal amino acid sequence was TVGGSLAEKGN which showed homology to other fungal RNases to a certain degree. The RNase exhibited maximal RNase activity at pH 5 and 80˚C. It demonstrated the highest ribonucleolytic activity toward poly(C), a relatively high activity toward poly(U), and a considerably weaker activity toward poly(A) and (G). The RNase inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase with an IC50 of 50 µM and reduced [3H-methyl]-thymidine uptake by L1210 leukemia cells and MBL2 lymphoma cells with an IC50 of 25 µM and 40 µM, respectively.