. Author manuscript; available in PMC: 2010 Apr 7.

Published in final edited form as: Biochemistry. 2010 Feb 2;49(4):782–792. doi: 10.1021/bi901446r

Table 1.

FRET Data for SecA Signal Peptide Binding

	Cys mutant	E_FRET^a	R (Å)^b	R₀ (Å)^c
SP22 data	190	0.70	29.2±0.5	33.7
	213	0.21	42.3±0.2	32.4
	256	0.53	26.1±0.2	26.7
	287	0.70	26.2±0.2	30.3
	292	0.33	30.8±1.1	27.5
	371	0.35	37.8±0.5	30.6
	402^d	0.08	58.3±2.1	39.5
	447^d	0.15	52.8±1.8	39.5
	470^d	0.16	51.8±1.9	39.5
	506	0.10	49.1±1.2	34.0
	661	0.53	33.9±3.9	33.7
	718	0.36	37.3±0.1	40.6
	827	0.21	42.4±0.2	33.7
SP2 data	190	0.59	32.1±0.7	33.7
	213	0.66	30.5±0.2	32.4
	256	0.53	39.4±0.3	33.7
	292	0.63	31.1±0.2	27.5
	827	0.50	33.9±0.1	33.7

FRET efficiency (E_FRET) was measured by the quenching of the donor fluorescence intensity as described in Experimental Procedures.

The donor–acceptor distance (R) was calculated as described in Experimental Procedures.

The Förster energy transfer distance defined as 50% efficient.

The FRET fluorescent dye pair used included Alexa Fluor-488 and Alexa Fluor-555.