Ivana Nikšić-Franjić1, Benoit Colasson2, Olivia Reinaud2,
Aleksandar Višnjevac1, Ivo Piantanida1
1Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
2Université de Paris – Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR 8601, 45 rue des Saints Pères, 75006, Paris, France
Calixarenes are remarkable supramolecules well known for their ability to bind to many biological molecules including nucleic acids fragments and DNA/RNA polymers.1 We have developed three generations of specially designed calix[4]- and calix[6]arenes bearing methylimidazole coordination arms or a TMPA capped unit (Tris(2-pyridylmethyl)amine) grafted at one of the rims.2 Series of these calixarenes have been studied for their ability to recognize the specific portion of variety of polynucleic chains.3 Based on these results, we have identified X6Me3ImMe3(TZMeNMe3+)3 as one of the most promising candidates DNA minor groove binders. We are reporting here on the unsuccessful crystallization screening of the non-covalent complex [(5′-CATATATATG-3′)2∙∙∙X6Me3ImMe3(TZMeNMe3+)3]. Crystallization experiments for cationic methylimidazole calix[6]arene and Cu2+ /Zn2+-calixarene complexes with double strand oligonucleotide (5′-CAT ATA TAT G-3′) were performed in different screen solutions that are usually employed for protein crystallization: Index, Memstart+Memsys, Midas, Wizard Classic 1+2, Morpheus I, Morpheus II, Morpheus III, JCSG and SG1Eco (MD1-88-Eco). “Sea urchin” crystals, that based on the size and morphology could be DNA or calix-DNA crystals, were observed in Morpheus III screen but no diffraction was detected. Salt crystals were detected in Index, Memstart+Memsys and Wizard Classic 1+2 screens, while in Midas screen crystallization precipitate was observed. With Morpheus III and SG1Eco screens, crystals were not observed, while for JCSG and Morpheus I crystals did not diffract.
Keywords: calixarenes; DNA/RNA; molecular dynamics; mononucleotides; X-ray crystallography