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Publication Abstract from PubMed

A crystallographic fragment screen was carried out to identify starting points for the development of inhibitors of protein kinase Pim-1, a potential target for tumour therapy. All fragment hits identified via soaking in this study turned out to bind to the unusually hydrophobic pocket at the hinge region. The most potent fragments, two cinnamic acid derivatives (with a best IC(50) of 130 microM), additionally form a well defined hydrogen bond. The balance between hydrophobic and polar interactions makes these molecules good starting points for further optimization. Pim-2 inhibitors from a recently reported high-throughput screening campaign also feature a cinnamic acid moiety. Two of these Pim-2 inhibitors were synthesized, their potencies against Pim-1 were determined and their cocrystal structures were elucidated in order to determine to what degree the binding modes identified by fragment screening are conserved in optimized inhibitors. The structures show that the cinnamic acid moieties indeed adopt the same binding mode. Fragment screening thus correctly identified binding modes which are maintained when fragments are grown into larger and higher affinity inhibitors. The high-throughput screening-derived compound (E)-3-{3-[6-(4-aminocyclohexylamino)-pyrazin-2-yl]phenyl}acrylic acid (compound 1) is the most potent inhibitor of the cinnamic acid series for which the three-dimensional binding mode is known (IC(50) = 17 nM, K(d) = 28 nM). The structure reveals the molecular basis for the large gain in potency between the initial fragment hit and this optimized inhibitor.

A crystallographic fragment screen identifies cinnamic acid derivatives as starting points for potent Pim-1 inhibitors.,Schulz MN, Fanghanel J, Schafer M, Badock V, Briem H, Boemer U, Nguyen D, Husemann M, Hillig RC Acta Crystallogr D Biol Crystallogr. 2011 Mar;67(Pt 3):156-66. Epub 2011, Feb 15. PMID:21358046^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.