Fig. 4.

Effective sulfation energy. (A) A schematic of tyrosine sulfation where the tyrosine-containing peptide is structured and/or buried. For the sulfation to occur, substrate protein undergoes a local unfolding around the sulfated tyrosine. (B) The probability density of the effective binding energy E^eff for sulfated and non-sulfated sequences. E^eff separates the two sets of sequences more effectively, compared with ΔΔG_bind (Fig. 3B). The reference coefficient C of E^eff is chosen as −14.6 kcal/mol so that the two distributions intersect around zero. The Z-score between the two distributions is −1.03