摘要：

The interaction of rosaniline with various fractions of yeast nucleic acid and pentose nucleic acid from beef pancreas has been studied. It is concluded that the binding sites involve the phosphoric acid groups of which about 13% are available for binding. On the basis of the similar intrinsic binding constants and n values, it is suggested that a similar backbone structure exists among the nucleic acid samples studied. The interaction of rosaniline with the ribonuclease-resistant fractions of yeast pentose nucleic acid has been also studied, and the binding capacity of these resistant fractions is of the same order of magnitude as that of the parent nucleic acids. The binding capacity of the n1-type site (divalent anion) of the resistant fractions appears to be slightly greater than that of the parent PNA. It is suggested that this is due to a decrease in steric inhibition. In the case of the ribonuclease-phosphatase treated nucleic acid, the results of the binding process suggest that only one type of site is involved, and it would appear that this corresponds to the monovalent anion type. Correlation of the experimental pH titration curves with theoretical curves constructed from the known composition of various samples of nucleic acid, a ribonuclease-resistant fraction and a ribonuclease-phosphatase-resistant fraction indicates that some of the hydroxyl groups of guanine and/or uracil are unavailable for titration and may be covalently bound in a phosphate type bond. In the case of the ribonuclease-phosphatase treated nucleic acid, purine and pyrimidine analyses, periodate oxidation titers and ion-exchange analysis provide additional evidence for such a covalent linkage. Both PNA and the ribonuclease-resistant fraction have been subjected to periodate oxidation, and it appears that a D-riboside phosphate other than the 2′ or 3′ exists in the resistant fraction. Ultraviolet and infrared absorption spectra of both treated and untreated nucleic acids are similar and cannot be used effectively as a means of identification. X-Ray powder patterns suggest that some of the residues remaining after the action of ribonuclease and acid-phosphatase are partially crystalline.

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