Figure 18.

Dipeptide nitrile 1b and dipeptide alkyne 2b compared with the literature inhibitor CA-074 in the U251-MG cell lysate. (A) Turnover of internally quenched substrate Abz-GIVR↓AK(Dnp)-NH₂ (↓ indicates the cleavage site) as measured by increasing fluorescence intensities after preincubation for 30 min with the respective inhibitor. (B) Relative inhibition normalized to the inhibitory effect of CA-074 (mean ± SEM). The measurement was performed as a duplicate determination in assay buffer (pH 6.0) containing 0.5 mg/mL protein, 100 μM Abz-GIVRAK(Dnp)-NH₂, and 1% DMSO.