H. Zhao; A. Caflisch

Journal: Bioorg. Med. Chem. Lett.
Year: 2014
Volume: 24
Issue: 6
Pages: 1523-1527
DOI: 10.1016/j.bmcl.2014.01.083
Type of Publication: Journal Article

Binding Sites; Drug Evaluation, Preclinical; Humans; Intracellular Signaling Peptides and Proteins; Molecular Docking Simulation; Protein Binding; Protein Kinase Inhibitors; Protein Structure, Secondary; Protein Structure, Tertiary; Protein-Tyrosine Kinases; ZAP-70 Protein-Tyrosine Kinase


The non-receptor tyrosine kinase Syk (spleen tyrosine kinase) is a pharmaceutical relevant target because its over-activation is observed in several autoimmune diseases, allergy, and asthma. Here we report the identification of two novel inhibitors of Syk by high-throughput docking into a rare C-helix-out conformation published recently. Interestingly, both compounds are slightly more active on ZAP70 (Zeta-chain-associated protein kinase 70), which is the kinase closest to Syk in the phylogenetic tree of human kinases. Taken together, the docking pose and experimental results suggest that the higher affinity of the inhibitors for ZAP70 than Syk originates from a more populated C-helix-out conformation in ZAP70. The latter observation is congruent with the 100-fold lower intrinsic activity of ZAP70 than Syk, as the C-helix-out conformation is inactive. The pharmacophore features of DFG-in, C-helix-out compounds are analyzed in relation to DFG-out inhibitors.