How stable are circular oligonucleotides?

Circular DNAs and RNAs do not have 5' or 3' ends and are therefore very resistant to exonuclease-mediated degradation and are more stable than their linear counterparts.

Circular ssDNA is very stable and highly resistant to exonuclease degradation. This is illustrated in Lane #3 and #5 of a PAGE gel. 


The treatment of linear and circular single stranded DNA with exonuclease I shows that circular single stranded DNA is very stable to degradation by exonucleases.