Table 2.

Thermodynamics of LexA binding to recA operator mutants

Inhibitor sequencea	Kd(app) (nM)	Kd(calc) (nM)b	ΔG (kJ/mol)	|ΔΔG|c (kJ/mol)
5′-CGAACATATGTTCG-3′	993	0.17	−34.2	0
5′-CGAACATGCGTTCG-3′	767	0.22	−34.9	0.7
5′-AGAACATGCGTTCG-3′	391	0.42	−36.6	2.4
5′-CGAACTTGCGTTCG-3′	337	0.49	−36.9	2.7
5′-CGAACCTGCGTTCG-3′	299	0.56	−37.2	3.3
5′-CGAACAAGCGTTCG-3′	268	0.62	−37.5	3.4
5′-GGAACATGCGTTCG-3′	166	1.0	−38.6	4.4
5′-CGAATATGCGTTCG-3′(wt)	40.3	4.6	−42.2	8.0
5′-CAAACATGCGTTCG-3′	36.3	5.2	−42.4	8.2
5′-CGAATGTGCGTTCG-3′	30.4	6.4	−42.9	8.7
5′-CGAATACGCGTTCG-3′	25.6	7.8	−43.4	9.1
5′-AGAATATGCGTTCG-3′	19.0	11.4	−44.0	9.8
5′-CGAATTTGCGTTCG-3′	18.9	11.5	−44.1	9.9
5′-CGAATAAGCGTTCG-3′	14.2	17.1	−44.8	10.6
5′-CGAATCTGCGTTCG-3′	12.8	20.0	−45.0	10.8
5′-GGAATATGCGTTCG-3′	7.7	53.0	−46.3	12.1
recA operator base substitutions that prevent LexA binding
5′-TGAATATGCGTTCG-3′	5′-CTAATATGCGTTCG-3′
5′-CCAATATGCGTTCG-3′	5′-CGTATATGCGTTCG-3′
5′-CGCATATGCGTTCG-3′	5′-CGGATATGCGTTCG-3′
5′-CGATTATGCGTTCG-3′	5′-CGACTATGCGTTCG-3′
5′-CGAGTATGCGTTCG-3′	5′-CGAAGATGCGTTCG-3′
5′-CGAAAATGCGTTCG-3′	5′-CGAATAGGCGTTCG-3′
5′-CTAACATGCGTTCG-3′	5′-CCAACATGCGTTCG-3′
5′-CGAATATGCATTCG-3′	5′-CGAATATGCGTTTG-3′
5′-CAAACATGCATTCG-3′	5′-CAAACATGCGTTTG-3′

^aBases in boldface are changes relative to the wild-type recA operator.

^bK_d values were determined by calculating K_I from the relationship K_d(app) = K_d(recA) (1 + [I]/K_I) and then multiplying the K_I values by the ratio K_d(recA)/K_{I (wt)}.

^cΔΔG values are given as absolute values.