Synthesis, Enzymatic Evaluation, and Docking Studies of Fluorogenic Caspase 8 Tetrapeptide Substrates

• DOI: 10.1002/cmdc.200900356
• Publication Date: 2009-11-13T16:39:05Z
• Authors: Przemysław Reszka; Riad Schulz; Karen Methling; Michael Lalk; Patrick J. Bednarski
• Keywords: Tetrapeptide; Docking (animal); Molecular model; AutoDock

The synthesis, enzymatic evaluation, and molecular modeling studies of new fluorogenic tetrapeptide-based substrates selective for caspase 8, having the general structure Ac-IETD-AXX, are described. Various fluorescent reporter groups (AXX), i.e., 3- 4-substituted coumarins quinolin-2(1H)-ones were synthesized by von Pechmann condensation. They subsequently coupled with caspase-8-selective tetrapeptide Ac-IETD-OH under newly developed synthetic conditions to give desired in good yields high enantiomeric purity. Based on K(M) V(max) values, compounds proved be excellent recombinant human 8. In contrast, values same as 3 approximately 10-20-fold higher. Molecular based X-ray crystal structures both caspases 8 revealed that there is sufficient room within active sites accommodate moderately bulky substituents 4-positions quinolin-2(1H)-ones. Automated docking into program AutoDock gave similar published crystallographic bound form an irreversible inhibitor. calculated binding energies either or showed little difference between substrates, consistent data. addition, (DeltaG) considerably more negative than those 3, also A possible interaction might explain selectivity IETD motif over discussed.