Ks. Jung et al., CONFORMATION OF SINGLE-STRANDED POLY(DA) AND ITS INTERACTION WITH 4',6-DIAMIDINO-2-PHENYLINDOLE, Bulletin of the Korean Chemical Society, 18(5), 1997, pp. 510-514
We studied the interaction of 4',6-diamidino-2-phenylindole (DAPI) wit
h single stranded poly(dA) using optical spectroscopic methods, includ
ing absorption, circular dichroism (CD), and fluorescence spectroscopy
. The temperature-dependent conformation of poly(dA) was also investig
ated. The conformation of poly(dA) varied with temperature, which is e
xplained by the stacking-destacking process of the adenine bases, resu
lting from the sugar conformation. The hypochromicity and red-shift in
the absorption spectroscopy, the lack of CD change in the drug absorp
tion region, and the fluorescence behavior, especially a great accessi
bility of the I, quencher to the poly(dA)-bound DAPI, suggest that DAP
I binds to the outside of poly(dA). The Job plot for the DAPI-poly(dA)
mixture demonstrated that a stoichiometry of one DAPI molecule binds
to the one phosphate of poly(dA).