Structural and Affinity Analyses of G-Quadruplex DNA Aptamers for Camptothecin Derivatives

Pharmaceuticals

Hiroto Fujita¹  Yuri Imaizumi¹  Yuuya Kasahara¹  Shunsuke Kitadume¹  Hiroaki Ozaki¹  Masayasu Kuwahara¹ 

[1] Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan

关键词: DNA aptamer;    G-quadruplex;    camptothecin (CPT);    circular dichroism (CD) spectroscopy;    fluorescence titration;    fluorescence polarization (FP) assay;   

DOI  :  10.3390/ph6091082

来源: mdpi

【 摘 要 】

We recently selected DNA aptamers that bind to camptothecin (CPT) and CPT derivatives from a 70-mer oligodeoxyribonucleotide (ODN) library using the Systematic Evolution of Ligands by EXponential enrichment (SELEX) method. The target-binding activity of the obtained 70-mer CPT-binding DNA aptamer, termed CA-70, which contains a 16-mer guanine (G)-core motif (G₃TG₃TG₃T₂G₃) that forms a three-tiered G-quadruplex, was determined using fluorescence titration. In this study, truncated fragments of CA-70 that all have the G-core motif, CA-40, -20, -19, -18A, -18B, -17, and -16, were carefully analyzed. We found that CA-40 retained the target-binding activity, whereas CA-20, -19, and -18B exhibited little or no binding activities. Further, not only CA-18A but also the shorter length fragments CA-17 and -16 clearly retained the binding activity, indicating that tail strands of the G-quadruplex structure can significantly affect the target binding of G-quadruplex DNA aptamers. Further analyses using circular dichroism (CD) spectroscopy and fluorescence polarization (FP) assay were conducted to investigate the structure and affinity of G-quadruplex DNA aptamers.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.