On the action of ribonuclease.

In an earlier investigation from this laboratory (I), prostatic phosphomonoesterase was used for the partition of the phosphomonoester and phosphodiester groups in ribonuclease digests. It was shown that the inorganic phosphate formed during incubation of ribonuclease digests with phosphatase originated practically exclusively from the acid-stable (pyrimidine) nucleotide groups of ribonucleic acids. It was concluded that the action of ribonuclease involved specifically pyrimidine nucleotide groups of yeast ribonucleic acids. Independent observations from several other laboratories likewise suggest the assumption that the action of ribonuclease involves specifically, or at least preferentially, the pyrimidine nucleotide groups of yeast ribonucleic acid (2-4). It is still unknown, however, how many of the total pyrimidine nucleotide groups of yeast ribonucleic acid are hydrolyzable by ribonuclease. This question is the problem of the present investigation.