Key points are not available for this paper at this time.
Many methods have been described in the litera- ture for determining the activity of ribonuclease (McDonald, 1955); most of these employ ribo- nucleic acid as substrate and are not suitable for kinetic investigations because it is not clear which step in the reaction sequence is measured. The action of the enzyme on ribonucleic acid or pyr- imidine nucleotide 3'-esters involves two successive
Crook et al. (1960) studied this question.