Binding of Hoechst 33258 and its derivatives to DNAстатья
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Дата последнего поиска статьи во внешних источниках: 17 января 2017 г.
Аннотация:In the present work, we employed UV-VIS spectroscopy, fluorescence methods, and circular
dichroism spectroscopy (CD) to study the interaction of dye Hoechst 33258, Hoechst 33342,
and their derivatives to poly[d(AT)]·poly[d(AT)], poly(dA)·poly(dT), and DNA dodecamer
with the sequence 5ʹ-CGTATATATACG-3ʹ. We identified three types of complexes formed
by Hoechst 33258, Hoechst 33342, and methylproamine with DNA, corresponding to the
binding of each drug in monomer, dimer, and tetramer forms. In a dimer complex, two
dye molecules are sandwiched in the same place of the minor DNA groove. Our data show
that Hoechst 33258, Hoechst 33342, and methylproamine also form complexes of the third
type that reflects binding of dye associates (probably tetramers) to DNA. Substitution of a
hydrogen atom in the ortho position of the phenyl ring by a methyl group has a little effect
on binding of monomers to DNA. However it reduces strength of binding of tetramers to
DNA. In contrast, a Hoechst derivative containing the ortho-isopropyl group in the phenyl
ring exhibits a low affinity to poly(dA)·poly(dT) and poly[d(AT)]·poly[d(AT)] and binds to
DNA only in the monomer form. This can be attributed to a sterical hindrance caused by the
ortho-isopropyl group for side-by-side accommodation of two dye molecules in the minor
groove. Our experiments show that mode of binding of Hoechst 33258 derivatives and their
affinity for DNA depend on substituents in the ortho position of the phenyl ring of the dye
molecule. A statistical mechanical treatment of binding of Hoechst 33258 and its derivatives
to a polynucleotide lattice is described and used for determination of binding parameters of
Hoechst 33258 and its derivatives to poly[d(AT)]·poly[d(AT)] and poly(dA)·poly(dT).
Key words: Hoechst 33258; Hoechst 33342; Methylproamine; UV-VIS spectroscopy; Circular
dichroism; Side by side motif; Statistical mechanical treatment; Molecular modeling.