. Author manuscript; available in PMC: 2014 Jan 27.

Published in final edited form as: Biochemistry. 2012 May 1;51(19):4062–4071. doi: 10.1021/bi300243z

Table 4.

FRET-based determination of intermolecular distances for IpaB-IpgC complexes.

Protein	No IpgC		1 μM IpgC
Protein	FRET^a efficiency (%)	Distance (Å)^b	FRET efficiency (%)	Distance (Å)^c
IpaB^N28.226	47.1 ± 3.2	21.4	37.9 ± 14.8	22.8
IpaB^C28.226	74.5 ± 5.9	17.6	46.1 ± 6.8	21.6
IpaB^N1.226	37.6 ± 3.3	22.8	6.5 ± 3.6	32.8

FRET was measured using the intrinsic probe W105 as the donor for IpaB^28.226 or IpaB^1.226 to either an N- or C-terminal Alexa350 acceptor probe as described in methods. FRET efficiencies and distances were calculated using equations 1 and 2, respectively.

This distance is measured with the realization that it may not precisely represent the distance separating the two probes because of homodimer formation.

This calculation refers to the condition in which IpaB/IpgC heterodimers are formed and should represent an accurate distance between the two probes.