MS40-P04 Crystallization of the quadruplex (GGGGTTTTGGGG)2 with BRACO19 Rositsa Nikolova (Institute of Mineralogy and Crystallography, Sofia, Bulgaria) Hristina Sbirkova-Dimitrova (Institute of Mineralogy and Crystallography, Sofia, Bulgaria) Rusi Rusev (Institute of Mineralogy and Crystallography, Sofia, Bulgaria) Louiza Dimova (Institute of Mineralogy and Crystallography, Sofia, Bulgaria) Boris Shivachev (Institute of Mineralogy and Crystallography, Sofia, Bulgaria)email: of the approaches for to development of new anticancer compounds focuses on the design and screening of compounds, small molecules that interact selectively with cancers cells. As telomeres are G-rich noncoding regions located at the end of chromosomes. The telomere shortens with each cell division. When it reaches a critical length it triggers DNA damage response which leads to cell death. Cancer cells have active telomerase (responsible for the maintenance of telomeres) that maintain a shorten but not critical telomere length, provoking those cells to unlimited cell division. G-rich telomeres are in practice forming G-quadruplex structures in vivo. Ligands that selectively bind and stabilize G-quadruplex, are interfering with telomerase activity: maintenance and elongation of telomere. We report on the interaction of the (GGGGTTTTGGGG)2 sequence with the small molecule BRACO-19. In addition, single crystal of the DNA complex with BRACO19 were grown (Figure 1). The initial crystallization conditions included KCl, KCaCO pH7.5, MgCl2, Spermine and MPD. The crystals were brownish in color and diffracted up to 2.5 Å resolution. In order to solve the crystal structure, currently diffraction limit and crystal quality are optimized through modification of the crystallization conditions.

The authors are grateful to the Bulgarian national Science fund grant T02/14 for the financial support.
Keywords: G-4, quadruplex, BRACO19