Biomedical Engineering Reference
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Fig. 3.4 Understanding folding process of single G-quadruplex aptamer using the
-hemolysin-
based nanopore sensor. (a) The sequence and structure of the G-quadruplex formed by the
thrombin-binding aptamer (TBA) (
left
), the two G-tetrad planes coordinated by a metal ion in
the TBA G-quadruplex (
middle
), and molecular graph showing the encapsulation of a single TBA
G-quadruplex in the nanocavity of the
a
-hemolysin pore (
right
). (b) Current traces showing the
interaction of G-quadruplex and the
a
-hemolysin pore in the presence of K
+
(
left
) and Na
+
(
right
),
and models. The signature long blocks with a terminal spike are generated by trapping and
unfolding of a G-quadruplex in the pore, and the co-existing short blocks by the translocation
of linear form TBA DNA. (c) Characteristic blocks produced by tag-TBA (
top
) and the model
showing the location and change in position of the G-quadruplex in the cavity (
bottom
)[
99
,
100
].
Reprinted with permission from
J. Phys. Chem. B
112:8354-9360 (2008) and
Nucleic Acids
Research
37:972-982 (2009)
a
intervened between adjacent tetrads in coordination with eight carbonyls of guanine
bases for stabilization [
10
,
58
]. Native G-quadruplexes frequently occurs at the end
of telomeres in the human genome where they participate in gene regulation [
2
].
G-quadruplexes in the human genome [
95
,
96
] are important drug targets [
49
,
64
,
85
] because they are associated with many gene control-related mechanisms [
2
,
26
,
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