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. Author manuscript; available in PMC: 2014 Jan 1.
Published in final edited form as: Rep Prog Phys. 2012 Dec 18;76(1):016601. doi: 10.1088/0034-4885/76/1/016601

Figure 7.

Figure 7

Three and four color FRET (Lee et al., 2010a). (a) Schematic of 4-color FRET setup with shutters for alternating excitation. (b) Diagram of energy transfer between 4 dyes. With alternating excitation, it is possible to determine all six pairwise distances between the dyes. (c) Strand exchange by RecA filament demonstrated in real time by 4-color FRET. Simultaneously observing two pairs of dyes revealed various types of exchanging mechanism, depending on which part of the DNA strand initializes the exchange.