ELECTROPHORETIC SEPARATION OF NUCLEIC ACID COMPONENTS 281 



Fig. 6. The dissociation curves of GU and GU! and the electrophoresis at pH 7.4 

 of GU! and GU (produced by the ribonuclease treatment of GU!).'" GU differs from 

 GU! in having an extra (secondary phosphoric OH) acidic group. The substances were 

 placed at the top of the paper, GU! on the left and GU on the right. 



The dinucleotides with cycUc terminal phosphate groups are separated 

 from the corresponding nucleotides with singly esterified terminal phos- 

 phates on the initial chromatogram. These are also separated on electro- 

 phoresis at pH 7.4 when the noncyclic dinucleotide bears an additional 

 charge due to the dissociated secondary phosphate group (Figure 6). The 

 polynucleotides in incomplete acid hydrolysates of PNA may be separated 

 in the same way. Although polynucleotides bearing cyclic phosphate groups 

 are absent, these hydrolysates also contain polynucleotides with terminal 

 purine nucleotide residues; consequently, more than one electrophoretic 

 run is often necessary to obtain individual polynucleotides. 



Isomers such as AGU, GAU, etc. are not separated on electrophoresis. 



