TY - JOUR
T1 - Resolving Ultrafast Photoinitiated Dynamics of the Hachimoji 5-aza-7-deazaguanine Nucleobase
T2 - Impact of Synthetically Expanding the Genetic Alphabet1
AU - Krul, Sarah E.
AU - Costa, Gustavo J.
AU - Hoehn, Sean J.
AU - Valverde, Danillo
AU - Oliveira, Leonardo M.F.
AU - Borin, Antonio Carlos
AU - Crespo-Hernández, Carlos E.
N1 - Funding Information:
S.E.K., S.J.H. and C.E.C.H. acknowledge funding from the National Science Foundation (Grant No. CHE‐1800052). G.J.C. thanks CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) for research fellowship (Project number 88882.328213/2019‐01). D. V. acknowledges funding from the Fonds de la Recherche Scientifiques de Belgique (F.R.S.‐FNRS) under the grant F.4534.21 (MIS‐IMAGINE). L.M.F.O. thanks CAPES for research fellowship (Project number 88882.328237/2019‐01). A.C.B. thanks CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for research fellowship (project number 311821/2021‐9) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for the research grant. The authors acknowledge the services and compute time provided by the Superintendência de Tecnologia da Informação da Universidade de São Paulo.
Funding Information:
S.E.K., S.J.H. and C.E.C.H. acknowledge funding from the National Science Foundation (Grant No. CHE-1800052). G.J.C. thanks CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) for research fellowship (Project number 88882.328213/2019-01). D. V. acknowledges funding from the Fonds de la Recherche Scientifiques de Belgique (F.R.S.-FNRS) under the grant F.4534.21 (MIS-IMAGINE). L.M.F.O. thanks CAPES for research fellowship (Project number 88882.328237/2019-01). A.C.B. thanks CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for research fellowship (project number 311821/2021-9) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for the research grant. The authors acknowledge the services and compute time provided by the Superintendência de Tecnologia da Informação da Universidade de São Paulo.
Publisher Copyright:
© 2022 The Authors. Photochemistry and Photobiology published by Wiley Periodicals LLC on behalf of American Society for Photobiology.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - The guanine derivative, 5-aza-7-deazaguanine (5N7CG) has recently been proposed as one of four unnatural bases, termed Hachimoji (8-letter) to expand the genetic code. We apply steady-state and time-resolved spectroscopy to investigate its electronic relaxation mechanism and probe the effect of atom substitution on the relaxation mechanism in polar protic and polar aprotic solvents. Mapping of the excited state potential energy surfaces is performed, from which the critical points are optimized by using the state-of-art extended multi-state complete active space second-order perturbation theory. It is demonstrated that excitation to the lowest energy 1ππ* state of 5N7CG results in complex dynamics leading to ca. 10- to 30-fold slower relaxation (depending on solvent) compared with guanine. A significant conformational change occurs at the S1 minimum, resulting in a 10-fold greater fluorescence quantum yield compared with guanine. The fluorescence quantum yield and S1 decay lifetime increase going from water to acetonitrile to propanol. The solvent-dependent results are supported by the quantum chemical calculations showing an increase in the energy barrier between the S1 minimum and the S1/S0 conical intersection going from water to propanol. The longer lifetimes might make 5N7CG more photochemically active to adjacent nucleobases than guanine or other nucleobases within DNA.
AB - The guanine derivative, 5-aza-7-deazaguanine (5N7CG) has recently been proposed as one of four unnatural bases, termed Hachimoji (8-letter) to expand the genetic code. We apply steady-state and time-resolved spectroscopy to investigate its electronic relaxation mechanism and probe the effect of atom substitution on the relaxation mechanism in polar protic and polar aprotic solvents. Mapping of the excited state potential energy surfaces is performed, from which the critical points are optimized by using the state-of-art extended multi-state complete active space second-order perturbation theory. It is demonstrated that excitation to the lowest energy 1ππ* state of 5N7CG results in complex dynamics leading to ca. 10- to 30-fold slower relaxation (depending on solvent) compared with guanine. A significant conformational change occurs at the S1 minimum, resulting in a 10-fold greater fluorescence quantum yield compared with guanine. The fluorescence quantum yield and S1 decay lifetime increase going from water to acetonitrile to propanol. The solvent-dependent results are supported by the quantum chemical calculations showing an increase in the energy barrier between the S1 minimum and the S1/S0 conical intersection going from water to propanol. The longer lifetimes might make 5N7CG more photochemically active to adjacent nucleobases than guanine or other nucleobases within DNA.
UR - http://www.scopus.com/inward/record.url?scp=85136554015&partnerID=8YFLogxK
U2 - 10.1111/php.13688
DO - 10.1111/php.13688
M3 - Article
AN - SCOPUS:85136554015
SN - 0031-8655
VL - 99
SP - 693
EP - 705
JO - Photochemistry and Photobiology
JF - Photochemistry and Photobiology
IS - 2
ER -