Table 2.

RevTetR effector and tetO operon-binding affinities

	ATC-binding constantsa	tetO-Binding constantsb
	+[Mg-ATC]+ KA [·107 M−1]c	+[Mg-ATC]+ KA [·107 M−1]c	+ATC KA [·107 M−1]c	−ATC KA [·107 M−1]c
Wild-type TetR	≥100d	0.04e	0.02	560e
revTetR1	4.5	320	190	NDf
revTetR2	2.4	140	7.8	ND
revTetR4	0.9	64	2.4	ND

^aATC-binding constants (association constants, K_A) have been determined in vitro using fluorescence titration by a direct titration of the TetR variants with [Mg-ATC]⁺ (45,46).

^btetO-Binding constants have been determined by SPR measurements, as described (15).

^cStandard deviations typically range from 10% to 40%.

^dThe affinity to wild-type TetR is too large to be determined by this method.

^eValues taken from ref. (15).

^fND = not detectable. The binding constant was below 10⁵ M⁻¹, which is too low for quantification.