Table 1.

Summary of substrates and oligonucleotide excision reactions

Sequence context†	Covalent C4′ modification	NER activity‡	ΔTm of 19-mer duplexes§
∗
CTTCGAAC	C4′ selenophenyl adduct	≤0.05%	−0.9°C
GAAGCTTG
∗
CTTCGAAC	C4′ selenophenyl adduct	1.01  ± 0.11%	−9.0°C
GAAGCCTG
∗
CTTCGAAC	C4′ selenophenyl adduct	7.34  ± 0.88%	−15.6°C
GAAGGCCG
∗
CTTCGAAC	C4′ inversion	≤0.05%	−1.2°C
GAAGCTTG
∗
CTTCGAAC	C4′ inversion	0.46  ± 0.08%	−7.5°C
GAAGCCTG
∗
CTTCGAAC	C4′ inversion	4.55  ± 0.37%	−15.3°C
GAAGGCCG
CTTCGAAC	None	≤0.05%	−8.3°C
GAAGCCTG
CTTCGAAC	None	≤0.05%	−15.8°C
GAAGGCCG
∗
CTTCGAAC	C4′ pivaloyl adduct	≤0.05%	−1.0°C
GAAGCTTG
∗
CTTCGAAC	C4′ pivaloyl adduct	12.53  ± 2.93%	−14.2°C
GTTTCTTG
CTTCGAAC	None	≤0.05%	−14.4°C
GTTTCTTG

^†Asterisks indicate the sites of C4′ backbone modification 

^‡Fractions of excised fragments after 40 min at 30°C. Mean values of 4–7 determinations ±SD. The AAF–C⁸–guanine adduct in the same sequence yielded 3.99 ± 1.20% excised duplexes. 

^§Changes in T_m of the central 19-mer duplex were determined as indicated in Materials and Methods. T_m of the unmodified duplex was 66.5°C.