Fig. 1.

(a) Comparison between and for the molten globule state of HLA. was computed by inverting Eq. 1 with replaced by for 0 M urea (for U > 10 M, see figure 4 of ref. 10). The coefficient of correlation is ρ = 0.94. (b) Comparison between the experimental R_g (blue line) (ref. 10 and T. Pertinhez and C. Redfield, personal communication) and the calculated R_g (red line) obtained by using the model of Eq. 2. The coefficient of correlation is ρ = 0.95. For comparison, we also show the R_g corresponding to groups 1, 2, and 3 of the molecular dynamics simulations of Paci et al. (13) (squares). (c) Probability distribution function P(R_g) in the native state (NS) and at 0, 5, and 10 M urea for the molten globule state of HLA calculated by using the model of Eq. 2. The corresponding values by Paci et al. (13) are indicated by arrows. The distribution of R_g for a random chain constrained only by the four disulfide bonds is also shown (SS). Values of R_g are in Å and U in M.