A novel ribonuclease from fruiting bodies of the common edible mushroom Pleurotus eryngii.

A ribonuclease with a temperature optimum of about 70 degrees C and a pH optimum of 6.5 was isolated from fruiting bodies of the mushroom Pleurotus eryngii. The ribonuclease was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel and S-Sepharose. It possessed a molecular mass of 16 kDa, and exhibited higher ribonucleolytic activity toward poly A and poly G and lower ribonucleolytic activity toward poly C and poly U. Its N-terminal sequence was distinctly different from those of other mushroom ribonucleases, and resembled that of Pleurotus tuber-regium only by 40%. Furthermore, its thermostability characteristics, polyhomoribonucleotide specificity and molecular mass were dissimilar to those of other mushroom ribonucleases.