Table 3.

R_G of Different Conformations of drkN SH3 Estimated from the smFRET Data or from Previous Ensemble SAXS Data

	Fexcha	Uexcha	Denatured Random Coil	Denatured Looped	<RG>FRETb (Å)	<RG>SAXS
Tris buffer (pH 7.5)	12.0 ± 0.9c	18.8 ± 1.0	–	–	15.5 ± 0.8	14.9 ± 0.5d
6 M GdmCl	12.0 ± 0.9c	–	22.5 ± 1.0	–	19.7 ± 0.8	21.9 ± 0.5d
–	–	22.5 ± 1.0	15.8 ± 0.2	20.6 ± 0.8

^aF_exch and U_exch are the folded and unfolded subpopulations under non-denaturing conditions.

^bThe population-weighted average R_G was calculated using Eq. 5 with the fractions obtained by fitting the smFRET histograms (Table 2).

^cThe R_G of the folded state was measured by SAXS (48) and adjusted for the presence of dye linkers (Section S5 in the Supporting Material).

^dThe ensemble average R_G was measured by SAXS in Tris buffer (17, 48) and in 2 M GdmCl (48).