TY - JOUR
T1 - Real-time Monitoring Excitation Dynamics of Human Telomeric Guanine Quadruplexes
T2 - Effect of Folding Topology, Metal Cation, and Confinement by Nanocavity Water Pool
AU - Ma, Chensheng
AU - Chan, Ruth C.T.
AU - Chan, Chris T.L.
AU - Wong, Allen K.W.
AU - Kwok, Wai Ming
PY - 2019/12/19
Y1 - 2019/12/19
N2 - Guanine(G)-rich human telomeric (HT) DNA repeats, crucial to maintenance of genome stability, readily form G-quadruplexes (GQs) with various folding topologies. Research on excitation dynamics of HT-GQs is, however, scarce. Herein, we report a femtosecond time-resolved fluorescence coupled with transient absorption investigation on HT-GQ with the basket-type structure in Na+ solution. The result unveils an unusual multichannel nonradiative mechanism dominated by states with varying character of charge transfer lasting ten and hundreds of picoseconds, accounting altogether for an overwhelming ∼85% of the overall deactivation involving proton transfer. Our comparative study shows that encapsulating the GQ in nanocavity water pool or changing it into hydrid-type topologies with the presence of K+ ions alter differently energies and lifetimes of these states, yet without affecting the nature of the electronic excitation involved. The finding of this work underscores a leading role of structural rigidity in regulating the interplay with the microenvironment of photoexcited monomolecularly folded HT-GQs.
AB - Guanine(G)-rich human telomeric (HT) DNA repeats, crucial to maintenance of genome stability, readily form G-quadruplexes (GQs) with various folding topologies. Research on excitation dynamics of HT-GQs is, however, scarce. Herein, we report a femtosecond time-resolved fluorescence coupled with transient absorption investigation on HT-GQ with the basket-type structure in Na+ solution. The result unveils an unusual multichannel nonradiative mechanism dominated by states with varying character of charge transfer lasting ten and hundreds of picoseconds, accounting altogether for an overwhelming ∼85% of the overall deactivation involving proton transfer. Our comparative study shows that encapsulating the GQ in nanocavity water pool or changing it into hydrid-type topologies with the presence of K+ ions alter differently energies and lifetimes of these states, yet without affecting the nature of the electronic excitation involved. The finding of this work underscores a leading role of structural rigidity in regulating the interplay with the microenvironment of photoexcited monomolecularly folded HT-GQs.
UR - http://www.scopus.com/inward/record.url?scp=85076136273&partnerID=8YFLogxK
U2 - 10.1021/acs.jpclett.9b02932
DO - 10.1021/acs.jpclett.9b02932
M3 - Journal article
C2 - 31769690
AN - SCOPUS:85076136273
SN - 1948-7185
VL - 10
SP - 7577
EP - 7585
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 24
ER -