PURIFICATION AND SOME PROPERTIES OF TWO ACID RIBONUCLEASES FROM THE MYCELIA OF ASPERGILL US NIGER

[摘要] Acid ribonuclease (RNase) was extracted from mycelia of Aspergillus niger 1617 and separated into two fractions designated acid RNases I (EC 3.1.27.1) and II (EC 3.1.27.3). Each fraction was partially purified and its enzymatic properties were examined. The molecular weight of acid RNase I was approximately 45, 000, and that of II was 13, 000. The optimal pH of acid RNase I was 3.5 and that of II, 4.5. Acid RNase I was inhibited markedly by Fe3+, Cu2+, Hg2+ and 5′-ATP, whereas II was inhibited markedly by Fe3+. Acid RNase I had no base specificity producing 3′-monophosphates of the four nucleosides and guanosine-2′, 3′-cyclic monophosphate. Acid RNase II was a guanine-specific RNase.Changes in the activity of acid RNases I and II were studied during culture on agar medium. The activity of acid RNases I and II increased and reached their maxima during the late phase of active growth. After their maxima, the activity of acid RNase I remained unchanged, while that of II decreased and finally disappeared.

[学科分类] 微生物学和免疫学