Superposition of the structures with heat treatment and with no heat-treatment of 1510-N K138A–234P10, and Fo − Fc electron densities of the heat-treatment complex (in a stereoview). Chains A and B are shown as cartoon loops and Cα traces, respectively. The peptide is shown as stick models. The complex with heat treatment is colored magenta (chains A and B) and red (peptide), and that with no heat treatment is colored cyan (chains A and B) and blue (peptide). The catalytic Ser97 residues of the heat-treatment complex are shown as red sticks. The electron densities of the peptide (residues 234–241) of the heat-treatment complex were calculated with phases from the model without the peptide.