TABLE 1.

Dissociation constants for the binding of RNAP to downstream fork junction probes with varying lengths of downstream duplex segment

The K_d values presented are averages from 2-3 individual experiments; the error is ±15%.

Probe	Kd
	nm
−11/+1	290
[−11/+7]SP[+2/+7]	61
[−11/+8]SP[+2/+8]	13
[−11/+9]SP[+2/+9]	1.9
[−11/+10]SP[+2/+10]	0.53
[−11/+12]SP[+2/+12]	0.30
[−11/+14]SP[+2/+14]	<0.2
−11/+1;−8T	3700
[−11/+14;−8T][+2/+14]	3.0
[−11/+16;−8T][+2/+16]	0.55
[−11/+20;−8T][+2/+20]	0.38