Structure of Yeast Ribonucleic Acid

Abstract

DURING recent years, facts have accumulated about the electrometric titration of samples of yeast ribonucleic acid isolated by various methods. All the titration curves published^1–6 show on analysis the presence of a group titrating in the range pH. 5·0–8·0; further, the pentose nucleic acid of the larvæ of Calliphora erythrocephala exhibits a similar dissociation⁷. The amount of this group present varies slightly with the samples used by different observers, but is generally of the order of 0·7 equiv. per statistical tetranucleotide in the polynucleotide, and it has been shown by Fletcher, Gulland and Jordan³ that this value approaches close to 1·0 equiv. per four atoms of phosphorus on correction for the phosphorus-deficiency commonly encountered in this nucleic acid. There appears to us to be no reason to suppose that the simplest interpretation of this observation is not the correct one, namely, that the group is a secondary phosphoric acid group ; this conclusion was reached by Fletcher, Gulland and Jordan³ and by Chantrenne⁴. The suggestion put forward by Allen and Eiler² that this group is a very weak primary phosphoric acid group could only be accounted for on the basis of a much greater disturbance of the interrelationships of the groups in the polynucleotide than has so far been contemplated.