Extended Data Table 2.

Viscosity dependence of the kinetic parameters obtained from the two-state maximum likelihood analysis, the transition path time, and the correlation time of the unfolded state dynamics obtained from the donor-acceptor cross-correlation at 22°C.

Gdmcl (M)	2.25	3.2	4.6	4.3	3.8
Glycerol (%)	0	50	55	58	61
Viscosity (η/η0)	1	10	36	38	53
EF	0.91 (0.0005)	0.84 (0.0004)	0.79 (0.0007)	0.79 (0.0004)	0.81 (0.0005)
EU	0.55 (0.0007)	0.50 (0.0005)	0.47 (0.0004)	0.49 (0.0005)	0.52 (0.0011)
k (ms-1)	0.85 (0.02)	0.48 (0.01)	0.46 (0.01)	0.40 (0.01)	0.56 (0.01)
pF	0.48 (0.008)	0.50 (0.006)	0.23 (0.004)	0.50 (0.005)	0.72 (0.005)
Transition path time (μs)	12.2 (2.0)	33.3 (2.7)	NA	39.1 (4.0)	49.0 (4.9)
Donor-acceptor cross correlation time in the unfolded state, 1/k (μs)	NA	0.80 (0.18)	3.4 (0.6)	3.8 (0.7)	6.1 (1.6)

Errors are standard deviations obtained from the diagonal elements of the covariance matrix calculated from the likelihood function.