TY - JOUR
T1 - Intermolecular proton transfer in microhydrated guanine-cytosine base Pairs
T2 - A new mechanism for spontaneous mutation in DNA
AU - Cerón-Carrasco, J. P.
AU - Requena, A.
AU - Zúñiga, J.
AU - Michaux, C.
AU - Perpète, E. A.
AU - Jacquemine, D.
PY - 2009/10/1
Y1 - 2009/10/1
N2 - Accurate calculations of the double proton transfer (DPT) in the adenine-thymine base pair (AT) were presented in a previous work [J. Phys. Chem. A 2009, 113, 7892.] where we demonstrated that the mechanism of the reaction in solution is strongly affected by surrounding water. Here we extend our methodology to the guanine-cytosine base pair (GC), for which it turns out that the proton transfer in the gas phase is a synchronous concerted mechanism. The O(G)-H-N(C) hydrogen bond strength emerges as the key parameter in this process, to the extent that complete transfer takes place by means of this hydrogen bond. Since the main effect of the molecular environment is precisely to weaken this bond, the direct proton transfer is not possible in solution, and thus the tautomeric equilibrium must be assisted by surrounding water molecules in an asynchronous concerted mechanism. This result demonstrates that water plays a crucial role in proton reactions. It does not act as a passive element but actually catalyzes the DPT.
AB - Accurate calculations of the double proton transfer (DPT) in the adenine-thymine base pair (AT) were presented in a previous work [J. Phys. Chem. A 2009, 113, 7892.] where we demonstrated that the mechanism of the reaction in solution is strongly affected by surrounding water. Here we extend our methodology to the guanine-cytosine base pair (GC), for which it turns out that the proton transfer in the gas phase is a synchronous concerted mechanism. The O(G)-H-N(C) hydrogen bond strength emerges as the key parameter in this process, to the extent that complete transfer takes place by means of this hydrogen bond. Since the main effect of the molecular environment is precisely to weaken this bond, the direct proton transfer is not possible in solution, and thus the tautomeric equilibrium must be assisted by surrounding water molecules in an asynchronous concerted mechanism. This result demonstrates that water plays a crucial role in proton reactions. It does not act as a passive element but actually catalyzes the DPT.
UR - http://www.scopus.com/inward/record.url?scp=70349441121&partnerID=8YFLogxK
U2 - 10.1021/jp906551f
DO - 10.1021/jp906551f
M3 - Article
C2 - 19736955
AN - SCOPUS:70349441121
SN - 1089-5639
VL - 113
SP - 10549
EP - 10556
JO - Journal of physical chemistry A
JF - Journal of physical chemistry A
IS - 39
ER -