STUDIES ON 2 NUCLEASES AND A RIBONUCLEASE FROM PHYSARUM POLYCEPHALUM PURIFICATION AND MODE OF ACTION

1. Two nucleases hydrolyzing both RNA and denatured DNA (Nucleases Pp-1 and Pp-1) and one ribonuclease (RNase Pp-4) were isolated from Physarum polycephalum in addition to the three RNases (RNases Pp-1, Pp-2 and Pp-3) reported in the preceding paper (1).2. They are thermolabile.3. The pH optima of nucleases Pp-1 and Pp-2 are pH4.5, and that of RNase Pp-4 is pH4.0.4. Nuclease Ppv1 and nuclease Pp-2 hydrolyze denatured DNA as well as RNA, but not native DNA.5. Nuclease Pp-1 hydrolyzes RNA forming nucleotides with terminal 3'-phosphate.6. Nuclease Pp-2 hydrolyzes RNA to produce nucleotides with terminal 5'-phosphate. It has no base specificity.7. RNase Pp-4 hydrolyzes RNA forming nucleotides bearing 5'-phosphate group with purine preference in regards to 3'-terminal nucleotides.8. Nuclease Pp-2 and RNase Pp-4 are strongly activated by Zn++. © 1969 BY THE JOURNAL OF BIOCHEMISTRY.