Table 3. Binding affinities of ATP and substrate ligands for AadA as determined by ITC.

nb, no binding detected.

AadA variant	K d(ATP) (M)	K d(streptomycin) (M)	K d(spectinomycin) (M)
Wild type	13 2	0.5 0.1	0.5 0.1
E87A	40 10	20 2	nb
E87Q	50 10	11 2	nb
W112F	20 5	0.8 0.1	0.6 0.1
D182N	16 3	0.7 0.1	>30
R192A	nb	>100	>30
K205A	nb	1.3 0.2	>10