Table 1.

Substrate specificity of EcChiP

The on rate (k_on) is given by (number of blocking events per second)/[sugar concentration]. In each case sugar concentration = 1.25 μm. The off rate (k_off) was obtained from the relationship k_off = 1/τ_c, where τ_c is the average residence (dwell) time (s) of the sugar molecule in the channel. The equilibrium binding constant is given by the relationship K = k_on/k_off. N.D. indicates that there were no well-resolved blocking events, so that the residence time could not be evaluated with confidence.

Substrate	cis side addition						trans side addition
	+100 mV			−100 mV			+100 mV			−100 mV
	kon	koff	K	kon	koff	K	kon	koff	K	kon	koff	K
	106m−1 s−1	s−1	m−1	106m−1 s−1	s−1	m−1	106m−1 s−1	s−1	m−1	106m−1 s−1	s−1	m−1
GlcNAc2		N.D.			N.D.			N.D.			N.D.
GlcNAc3		N.D.			N.D.			N.D.			N.D.
GlcNAc4	1	2,550 ± 320	390 ± 10	1.7	2,350 ± 255	700 ± 70	3	1,608 ± 25	1,900 ± 350	1	2,642 ± 136	380 ± 50
GlcNAc5	2	250 ± 19	8,000 ± 3,550	4	280 ± 12	14,300 ± 8,300	3	255 ± 3	11,000 ± 1,880	2	385 ± 6	5,200 ± 570
GlcNAc6	4	80 ± 1	50,000 ± 28,700	5	78 ± 1	64,000 ± 39,200	5	93 ± 2	54,000 ± 5,100	2	98 ± 1	20,400 ± 200