|
When the spermine, which is one of the polyamines containing cation in vivo, binds to DNA, it can increase the stability of DNA. At the same time, it can cause B-fortn to Z-form transformations of DNA. However, because we cannot determine the binding geometry of the spermine to DNA by using spectroscopic methods, nobody can show the accurate binding mechanism of a DNA-spermine complex. Thus, we used DAPI as a spectroscopic probe of spermine, which binding geometry was well known. At the result of base selective binding geometry of spermine to synthetic DNA, the concentration of spermine gets higher, it grows the hydrophobic environment of DAPI which bound the minor groove of adenine-thymine base pair. Simultaneously, spermine seems to bridge the backbones around the minor groove of poly[d(A-T)2]. So that, the intensity of fluorescence spectrum of that shows sudden increasement. In guanine-cytocine base pair, poly[d(G-C)2], we can suppose that spermine bind to the major groove of that, shoving out the DAPI which is partially intercalated between the base pocket across the major groove of it. In both cases, spermine doesn’t show the base selectivity against to DNA.
|