Fig. 4.

The folding pathways of R1516 (a) and R1617 (b). The rate constants shown are the folding and unfolding rates extrapolated to 0 M denaturant. In both cases, the N-terminal domain folds first, followed by the C-terminal domain. In R1617, there is also a low stability partly folded early intermediate (I₁) that has little secondary structure but can be detected by a dead-time change in fluorescence (6).