Guanine base pairing

The authors claim that these associations, which are destroyed in fixed compounds, play an important role in the calculation of Ty.The cases of 1,2,4-triazole-5-thiones 74 [97SA(A)699] and of pyridone dimers 15a-15a and 15a-15b were also studied [96MI(13)65]. (3) The recording of IR spectra in solution at different temperatures to determine the effect of the temperature on Kj-, for instance, in pyrazolinones [83JPR(325)238] and in cytosine-guanine base pairs [92MI(9)881]. (4) The determination of the equilibrium 2-aminopyridine/acetic acid 2-aminopyridinium acetate (see Section III.E) in the acid-base complex was carried out by IR (97NKK100). 

Groenhof G, Schafer LV, Boggio-Pasqua M, Goette M, Grubmuller H, Robb MA (2007) Ultrafast deactivation of an excited cytosine-guanine base pair in DNA. J Am Chem Soc 129 6812—6819... 

In particular, statements like this calculation consumed three weeks of CPU time on a CONVEX or this calculation involved 17 000 000 CSFs in the Cl expansion do not, in themselves say anything about the quality of the results. An all valence electron CCSD(T) calculation on the cytosine-guanine base pair using a split-valence basis would involve about 23 000 000 T and T2 amplitudes, for example, but the results... 

The SCF-MI method was also employed to study the influence of hydration on the WC cytosine-guanine base pair, investigating the ability to reproduce the hydration pattern present in the real system (the base pair in the DNA framework) [33]. The calculated water positions around the base pair were compared to those predicted by a knowledge-based approach employing crystallographic data [34]. The correspondence between averaged... 

Figure 17-11. Valence bond representations of the cytosine-guanine base pair in the relevant electronic states (adapted from Ref. [53])...

In all of these computations, there is a dense manifold of excited states present [83], Thus the computations are sensitive to dynamic electron correlation and the details of the reaction coordinates involved. In the cytosine-guanine base pair simulations, trajectory calculations proved to be necessary to determine the extent of the conical intersection that is actually accessible. Subsequent improvements in the level of theory used for the static calculation of single molecules will be possible, but these should be balanced against a more realistic treatment of vibrational kinetic energy and environmental effects (solvent/protein). 

Brown T, Kneale G, Hunter WN, Kennard O (1986) Structural characterization of the bromouracilo-guanine base-pair mismatch in a Z-DNA fragment. Nucl Acids Res 14 1801-1809... 

The bases found in RNA (ribonucleic acid) are the purine heterocyclics adenine (6-aminopurine) and guanine (2-amino-6-oxypurine) and their complementary pyrimidine bases uracil (2,4-dioxypyrimidine) and cytosine (2-oxy-4-aminopyrimidine), respectively (Section 1, Appendix). In RNA double-stranded duplexes adenine (A) base-pairs with uracil (U) via two hydrogen bonds (A=U) and guanine base-pairs with cytosine (C) via 3 hydrogen bonds (G=C). Adenine forms the nucleoside adenosine by an N-glycosidic link with the... 

Furge, L.L. and Guengerich, F.P. (1998) Pre-steady-state kinetics of nucleotide insertion following 8-oxo-7,8-dihydro-guanine base pair mismatches by bacteriophage T7 DNA polymerase exo. Biochemistry, 37, 3567-3574. 

Adenine-guanine base pairs occupy more space than is available in the interior of the double helix, whereas cytosine—thymine base pairs are too small to span the distance between the sites to which complementary bases are bonded. One would not normally expect to find such base pairs in DNA. 

Figure 4. Porphyrin dimers 1 and 2 formed via H bonds between cytosine-guanine base pairs.

It is also possible to find MECI for 2 -f 2 and 2 + 2 structures for this cycloaddition. Such structures He on the same seam (see F re 3.1) as the 2s + 2s structure just discussed. Thus the conditions of Eqns (3.6) and (3.7) hold, however, Q changes. (Q is the coulomb energy corresponding to the energy of the system if all the Ky were zero.) Thus the 2s + 2 and 2a 4" 2a conical intersections are much higher in energy. The same type of conical-intersection structure is also found for the ultrafast deactivation of an excited cytosine-guanine base pair in DNA. ... 

Abo-Riziq A, Crews B, Grace L, de Vries MS (2005) Microhydration of guanine base pairs. J Am Chem Soc 127(8) 2374-2375... 

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