TABLE 1.

Fluorescence lifetimes of single-tryptophan analogs of gramicidin

Gramicidin analog	α1	τ1 (ns)	α2	τ2 (ns)	〈τ〉* (ns)
W(11,13,15)BgA	0.08	3.38	0.92	0.50	1.57
W(9,13,15)BgA	0.13	3.51	0.87	0.57	1.98
W(9,11,15)BgA	0.10	3.00	0.91	0.40	1.58
W(9,11,13)BgA	0.11	4.14	0.89	0.58	2.25

The excitation wavelength was 297 nm and emission was set at 330 nm. All other conditions are as in Fig. 1. See Materials and Methods for other details. The sequence of the gramicidin analogs is as in Fig. 1 a.

^*Calculated using Eq. 5.