Degradation of nucleic acids with ozone. III. Mode of ozone-degradation of mouse proline transfer ribonucleic acid (tRNA) and isoleucine tRNA.

Abstract

The degradation of mouse [32P]Pro tRNA and [32P]Ile tRNA with O3 (concentration in inlet gas, 0.1 mg/l) was examined in aqueous solution (reaction time, 0-32 min) and sequence analysis of the products was performed by digestion with ribonuclease A or T1 according to Sanger''s method. The guanine moieties in the nuleobases were preferentially attacked by O3 and the cleavage of polynucleotidic linkages did not occur during ozonization. Pro tRNA was more degradable than Ile tRNA, probably as a result of differences in the locations of the guanine residues in their higher-order structures. The consecutive guanine residues in the anticodon and dihydrouracil (D) regions of Pro tRNA were most susceptible to degradation with O3. In the case of Ile tRNA, which did not have the consecutive guanine residues in the anticodon region, those in the D-loop, small (S) loop and the common stem were degraded. O3 started reacting with the guanine moieties located in the most exposed regions of the higher-order structure of tRNA.