Biology Reference
In-Depth Information
signal. In the presence of ligase activity, the break was joined,
preventing removal ofthe ferrocene-labeled segment.
1.3.3
DNA Association Interactions
1.3.3.1 Binding of low molecular mass compounds
DNAassociationinteractionsareofinterestforchemistry,molecular
biology, and medicine, particularly for drug discovery and envi-
ronmental/medical processes [59, 60]. They concern association
with both inorganic and organic compounds as well as various
typesofassistedinteractionssuchasmetalandmetalcomplex-DNA
chemistry [61]. DNA-based biosensors serve as effective screening
tools for
in vitro
tests of this large group of DNA interactions.
Due to the preconcentration effect within the DNA structure, the
detection/concentration determination of a trace low molecular
mass analyte orgroup of analytes could also be aresult of the study.
These noncovalent host-guest interactions are represented
mainly by [14]
(a) intercalation between the stacked basepairs ofdsDNA,
(b) binding atmajor orminorgrooves of the DNA doublehelix,and
(c) electrostatic interactions.
The intercalation as an insertion of guest molecules between
the stacked base pairs of the double helix structure leads to a
change in the dsDNA chain, which must lengthen and unwind
slightly. The intercalation can also have an influence on the
electrochemicalactivityoftheintercalator.Forinstance,doxorubicin
and complexes of transient metals with 1,10-phenanthroline or
ferrocene naphthalene diimideretain their redox response after the
intercalation, but some others, e.g., phenothiazines, do not show
significant current signals after the intercalation. Sometimes the
intercalation can result in secondary interactions that can be used
for the detection, e.g., electron transfer from the guanine residues
(using, say, the [Ru(bpy)
2
]
2
+
complex), or generation of ROS able
to initiate oxidative cleavage of ribose cycles in the primary DNA
sequence.
