CHAPTER 5 



Hydrolysis of Nucleic Acids and Procedures for the Direct 



Estimation of Purine and Pyrimidine Fractions by 



Absorption Spectrophotometry 



HUBERT S. LORING 



Page 



I. Hydrolysis of Nucleic Acids 191 



a. General Considerations 191 



1. Acid Hydrolysis of PNA 192 



a. Liberation of Purine Bases and Ribose 192 



b. Liberation of Inorganic Phosphate and Formation of Pyrimidine Nucleo- 

 tides 194 



c. Liberation of Pyrimidine Bases 195 



d. Formation of Di- and Oligonucleotides 196 



2. Acid Hydrolysis of DNA 196 



a. Liberation of Purine Bases 196 



b. Liberation of Pyrimidine Nucleotides and Free Bases 197 



3. Alkaline Hydrolysis of PNA 197 



a. Formation of Nucleosides 197 



b. Formation of Nucleotides 198 



c. Liberation of Acid Groups 199 



IL Estimation of Purine and Pyrimidine Components in PNA 199 



1. Chemical Fractionation of Purine Bases and Pyrimidine Nucleotides and 

 Their Estimation by Absorption Spectrophotometry 199 



2. Effect of Various Treatments on the Recovery of the Purine Bases and 

 the Pyrimidine Nucleotides 202 



3. Experimental Procedure for the Analysis of Ribonucleic Acids by 

 Adsorption Spectrophotometry 202 



4. Application to Purified Yeast Ribonucleic Acids 204 



5. Application to Purified Nucleoproteins, Particulate Components of Cells, 

 and Tissues • 205 



I. Hydrolysis of Nucleic Acids 



a. General Considerations 



The possible hydrolytic products of both pentose and deoxypentose 

 nucleic acids, PNA and DNA, respectively, include purine and pyrimidine 

 bases, pentose and pentose phosphate, nucleosides, nucleotides, and oli- 

 gonucleotides as well as various degradation products derived from the 

 various substances mentioned. It is characteristic of both types of nucleic 



191 



