Table 2.

Dissociation constants (K_d, nM) of Endo III for 30 bp DNA duplexes^[a]

Central base pair	Endo III
riboFTg(5R)-A	7 ± 1
riboFTg(5S)-A	< 0.01 (51±3%), 4.7±1 (47±2%)[b]
araFTg(5S)-A	6 ± 1 (>90%)[c]
T-A	10±2
riboFTg(5R)-G	7.4±0.9
riboFTg(5S)-G	< 0.01 (73±2%), 4.7±0.1 (27±1%)[b]
araFTg(5S)-G	~ 0.01 (38±1%), 10±2 (61±3%)[b]
T-G	8.3±0.9

^[a]All measurements were performed at 25°C with 10 pM DNA and various amounts of enzyme. Errors reported in dissociation constants are standard deviation of the average of at least three trials. The concentrations of enzyme are active enzyme concentrations.

^[b]The data fit best using a two-site binding isotherm that provides two K_d values with relative capacities indicated in closed parentheses.

^[c]DNA-enzyme complex of less than 10% with tighter K_d was observed.