A. Kuglstatter et al. / Bioorg. Med. Chem. Lett. 18 (2008) 1304–1307
1307
Figure 3. Surface representation of (a) OM99-23 and (b) tyramine 1 bound to the BACE-1 active site. The flap indicated in green adopts the closed
conformation in (a) and the open conformation in (b).
7. Ghosh, A. K.; Kumaragurubaran, N.; Tang, J. Curr. Top.
Med. Chem. 2005, 5, 1609.
Fragment screening efforts reveal that the tyrosine
metabolite tyramine and derivatives thereof bind to
the active site of BACE-1. Due to their low molecular
weight and high ligand efficiency these compounds serve
as ideal starting points for the design of BACE-1 inhib-
itors with CNS pharmacological activity. In addition,
the obtained structural information can be used for
morphing or scaffold hopping approaches to improve
other chemical lead series.
8. Coburn, C. A.; Stachel, S. J.; Li, Y. M.; Rush, D. M.;
Steele, T. G.; Chen-Dodson, E.; Holloway, M. K.; Xu, M.;
Huang, Q.; Lai, M. T.; DiMuzio, J.; Crouthamel, M. C.;
Shi, X. P.; Sardana, V.; Chen, Z.; Munshi, S.; Kuo, L.;
Makara, G. M.; Annis, D. A.; Tadikonda, P. K.; Nash, H.
M.; Vacca, J. P.; Wang, T. J. Med. Chem. 2004, 47, 6117.
9. Surface Plasmon Resonance measurements were per-
formed on a Biacore S51 instrument. BACE-1 was
immobilized (ꢀ12,000 RU) by standard amine coupling
chemistry on a CM-5 sensor. Binding experiments were
performed using acetate buffer (50 mM, pH 4.6, 150 mM
NaCl, 3 mM EDTA, 0.005% P20, and 4% DMSO) as the
running buffer. Compounds were dissolved in 100 mM
DMSO and subsequently diluted into acetate buffer in
order to adjust the final DMSO content and the concen-
tration of the respective compound. Hits were further
investigated for specific binding to the active site of the
enzyme by competition experiments using a high affinity
(KD = 40 nM) inhibitor of BACE-1 derived from the
substrate (pGlu-Val-Asn-statin-Val-Ala-Glu-Phen-am).
10. Murray, C. W.; Callaghan, O.; Chessari, G.; Cleasby, A.;
Congreve, M.; Frederickson, M.; Hartshorn, M. J.;
McMenamin, R.; Patel, S.; Wallis, N. J. Med. Chem.
2007, 50, 1116.
Acknowledgments
We thank Manfred Brockhaus for discussions and read-
ing of the manuscript and the staff of the synchrotron
facility Swiss Light Source (Paul Scherrer Institut, Villi-
gen, Switzerland) for their assistance and support. We
thank Josef Schneider and Heribert Dollt for compound
analytics.
Supplementary data
Supplementary data associated with this article can be
11. Kuntz, I. D.; Chen, K.; Sharp, K. A.; Kollman, P. A.
Proc. Natl. Acad. Sci. USA 1999, 96, 9997.
12. Hopkins, A. L.; Groom, C. R.; Alex, A. Drug Discov.
Today 2004, 9, 430.
13. The K246A surface mutant variant of BACE-1 ectodo-
main (20 mg/ml) was crystallized by vapor diffusion in
hanging drops at 20 ꢁC by mixing 1.5 ll protein solution
with 0.5 ll of 2.5 M sodium formate, 100 mM Hepes (pH
7.0). Crystals of space group P6122 with unit cell
References and notes
1. Citron, M.; Oltersdorf, T.; Haass, C.; McConlogue, L.;
Hung, A. Y.; Seubert, P.; Vigo-Pelfrey, C.; Lieberburg, I.;
Selkoe, D. J. Nature 1992, 360, 672.
2. Hills, I. D.; Vacca, J. P. Curr. Opin. Drug Discov. Dev.
2007, 10, 383.
3. Hong, L.; Koelsch, G.; Lin, X.; Wu, S.; Terzyan, S.;
Ghosh, A. K.; Zhang, X. C.; Tang, J. Science 2000, 290,
150.
4. Dunn, B. M. Chem. Rev. 2002, 102, 4431.
5. Hong, L.; Tang, J. Biochemistry 2004, 43, 4689.
6. Patel, S.; Vuillard, L.; Cleasby, A.; Murray, C. W.; Yon, J.
J. Mol. Biol. 2004, 343, 407.
˚
˚
dimensions a = b = 103 A, c = 169 A grew to a maximum
size of 100 · 100 · 400 lm3. Apo crystals were soaked for
8–16 h in a buffer containing 30–100 mM compound,
2.5 M sodium formate, 0.1 M sodium acetate (pH 4.5),
and 10% DMSO. X-ray diffraction data were collected at
beamline X06SA of the Swiss Light Source (Paul Scherrer
Institut, Villigen, Switzerland). The crystal structure of the
K246A variant protein was solved by molecular replace-
ment using coordinates of an unpublished BACE-1
ectodomain structure as search template.