Non-covalent complexes between bis-β-carbolines and double-stranded DNA: A study by electrospray ionization FT-ICR mass spectrometry (I)

The non-covalent complexes of five bis-β-carbolines alkaloids with three different double-stranded oligodeoxynucleotides d(GCGCGATCGCGC)2, d(GCGCAATTGCGC)2, and d(GCGAAATTTCGC)2 were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. These five antitumor compounds all showed DNA-binding abilities. Binding affinities in the order of 2 > 3, 4 > 5, and 1 with double-stranded DNA were obtained, which mean that the length of the linkage chain between two β-carbolines has a remarkable effect on the formation of the non-covalent complexes. Additionally, the preliminary results indicated that bis-β-carbolines had no notable sequence selectivities.