Table 1.

Enzymatic stability of linear and circular single-stranded oligonucleotides

Oligonucleotide	Sequences (5′-3′)a	3′-Exonuclease half-lifeb	Intact after 24 h (%)	5′-Exonuclease half-lifec	Intact after 24 h (%)
ON-1	(dT)19•dT	1	10.0
ON-2	dT•(dT)19			1	6.5
ON-3	Q(dT)23Y	0.7	2.7	8.2	13.3
ON-4	Z(dT)23	1.2	14.8	26.8	52.5
ON-5 (linear)	QaaAaCaGuGuUCUuGcUcUaUaAY	12.8	76.1	14.1	83.8
ON-6 (cyclic)	ZaaAaCaGuGuUCUuGcUcUaUaA	14.5	79.1	423.0	100.0

^aChemistry modifications legend: •, terminal PS linkage; dT, 2′-deoxythimidine; lower case nucleotides, 2′-OMe; upper case nucleotides in italics, 2′-F; Q, 6-azidohexyl-phosphate. For structures of Y and Z, see Scheme 1. Z denotes a cyclic oligonucleotide.

^bHalf-life value determined in hours and reported relative to that of the (dT)₁₉•dT control.

^cHalf-life value was determined in hours and reported relative to that of the dT•(dT)₁₉ control. First-order decay kinetics were assumed in calculation of half-lives. Data are representative of two independent experiments with similar results.