National Center for
3WB5: Crystal Structure of beta secetase in complex with (6S)-2-amino-3,6-dimethyl-6-[(1R,2R)-2-phenylcyclopropyl]-3,4,5,6-tetrahydropyrimidin-4-one
Conformational restriction approach to beta-secretase (BACE1) inhibitors III: effective investigation of the binding mode by combinational use of X-ray analysis, isothermal titration calorimetry and theoretical calculations
Bioorg. Med. Chem. (2013) 21 p.6506-6522
For further investigation of BACE1 inhibitors using conformational restriction with sp(3) hybridized carbon, we applied this approach to 6-substituted aminopyrimidone derivatives 3 to improve the inhibitory activity by reducing the entropic energy loss upon binding to BACE1. Among eight stereoisomers synthesized, [trans-(1'R,2'R),6S] isomer 6 exhibited the best BACE1 inhibitory activity, which was statistically superior to that of the corresponding ethylene linker compound (R)-3. Combinational examinations of the binding mode of 6 were performed, which included isothermal titration calorimetry (ITC), X-ray crystallographic structure analysis and theoretical calculations, to clarify the effect of our conformational restriction approach. From the ITC measurement, the binding entropy of 6 was found to be approximately 0.5kcal larger than that of (R)-3, which is considered to be affected by conformational restriction with a cyclopropane ring.