FIGURE 2.

Hydrogen bond network involving N-terminal residues of mature SplB protease is absent in GS-SplB precursor mimic. Activation of SplB protease precursor mimic (blue, GS-SplB; PDB code 4K1S) by proteolytic processing is associated with formation of an extended hydrogen bond network at the newly formed N terminus of mature SplB protease (green; PDB code 2VID). Residues Gly-(−2) through Asn-2 of the precursor mimic are not defined by electron density and therefore not present in the model. Hydrogen bonds in SplB are indicated as black dotted lines. Water molecules are not shown for clarity.