Fig. 2.

Quality of the calculated electron density. (A) Surface representation of the TbCatB-propeptide complex solved by molecular replacement using the mature TbCatB structure (11) as a search model. The solution revealed additional electron density (2F_obs – F_calc, 1σ, blue) of the propeptide (green) that is bound to the V-shaped substrate-binding cleft and of two carbohydrate structures (yellow) N-linked to the propeptide (B) and to the mature enzyme (C). The propeptide, as well as both carbohydrates, are well-defined within the electron density map (blue), which confirms that the phases are not biased by the search model. Color codes correspond to Fig. 1C.