STUDIES ON RIBONUCLEASES IN TAKADIASTASE

III. PURIFICATION AND PROPERTIES OF RIBONUCLEASE T₂

Abstract

1. RNase T₂ was partially purified from Takadiastase. Most purified preparation was almost homogeneous in zone-electrophoresis and free from RNase T₁.
2. RNase T is heat stable and has pH optimum at 4.5. It is inhibited by Cu⁺⁺ and activated by EDTA, PCMB and monoiodoacetate.
3. Specificity of RNase T₂ is very characteristic, namely it preferentially hydrolyses secondary phosphate ester bonds of adenosine-3'-phosphate.
4. RNase T₂ digestion of yeast RNA is not complete and a resistant fraction remains.
5. In the crude RNase T₂ fraction the existence of small amount of another RNase, perhaps hydrolysing phosphodiester bonds of pyrimidine nucleotides, was suggested.
The authors wish to thank Sankyo Co., Ltd. for the gift of “Takadiastase Sankyo”.