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. 2022 Oct 19;23(20):12548. doi: 10.3390/ijms232012548

Figure 3.

Figure 3

A pKa tuning switch is also implemented in caspases. (a) Zoom-in view on the active site of caspase-9 (pdb 1jxq). Active site residues are shown in pink sticks, the Z-VAD-fmk inhibitor is shown in blue sticks. (b) Sequence alignment of human caspases. The catalytic Cys285 residue is indicated by a red star. The pKa switch at position 288 is highlighted by a blue box. Uniprot IDs are specified in the material and methods section. (c) Activity of ΔCARD-caspase-9 and the ΔCARD-caspase-9-E288K mutant measured as turnover of the VAD-AMC substrate. (d) KM values of ΔCARD-caspase-9 and the ΔCARD-caspase-9-E288K mutant determined using the VAD-AMC substrate.