Pine seed ribonucleases. I. Preparation and properties

The enzyme preparation, about 100 fold purified, shows optimal activity at pH 4.8 and 5.9. This activity lessens rapidly at 40-60 degrees C, and retains 20% at 100 degrees C. These results of heat stability and optimal pH might suggest that the enzyme preparation contains two enzymes. The use of gel filtration clearly shows that pine RNAses are endonuclease.