Guanine-cytosine interactions

The adenine-uracil interaction that involves two hydrogen bonds (Ka = lO M VCDCls) is weak and nonspecific compared with the guanine-cytosine interaction, which involves three hydrogen bonds (Ka = 10 -10 M VCDCls) that are... 

Sarai, A., and M. Saito. 1985. Theoretical Studies on the Interaction of Proteins with Base Paris. II. Effect of External H-Bond Interactions on the Stability of Guanine-Cytosine and Non-Watson-Crick Pairs. Int. J. Quantum Chem. 28, 399-409. 

Guanine-Cytosine Base-Pair Interacting with Metal Cations... 

Jorgensen WL, Pranata J. Importance of secondary interactions in triply hydrogen bonded complexes guanine-cytosine vs uracil-2,6-diaminopvridine. J Am Chem Soc 1990 12 2008-2010. 

Since the suggestion of the sequential QM/MM hybrid method, Canuto, Coutinho and co-authors have applied this method with success in the study of several systems and properties shift of the electronic absorption spectrum of benzene [42], pyrimidine [51] and (3-carotene [47] in several solvents shift of the ortho-betaine in water [52] shift of the electronic absorption and emission spectrum of formaldehyde in water [53] and acetone in water [54] hydrogen interaction energy of pyridine [46] and guanine-cytosine in water [55] differential solvation of phenol and phenoxy radical in different solvents [56,57] hydrated electron [58] dipole polarizability of F in water [59] tautomeric equilibrium of 2-mercaptopyridine in water [60] NMR chemical shifts in liquid water [61] electron affinity and ionization potential of liquid water [62] and liquid ammonia [35] dipole polarizability of atomic liquids [63] etc. 

The minor base hypoxanthine (X) occurs in some transfer RNA s. It is comparable to guanine but lacks the N(2) amino group. Therefore, all hydrogen bonds can be formed with cytosine and uracil where this group is not essential. For the hypoxanthine-cytosine interaction, we can write the matrix ... 

The nature of the interaction between nucleic acid bases has been a continual source of fascination ever since the nature of the genetic code was unraveled. However, the numbers of atoms and electrons in these systems erected a high barrier to the application of accurate quantum mechanical methods for many years. For example, the guanine-cytosine (GC) pair contains 29 atoms and 136 electrons. 

Considerable attention has also been devoted by several investigators to the theoretical study of the potential curves for hydrogen bonds of the guanine-cytosine and adenine-thymine base pairs. An accurate representation of this potential is important because the genetic code is contained in this interaction. Lowdin has suggested that mutations may be a result of a shift in position of the hydrogen bond protons in the base units of DNA via proton tunneling. " The idea of proton... 

Yet another effect of the action of Ag" has been described, namely, its interaction with nucleic acids [112]. The Ag" ion interacts preferentially with the bases found in DNA rather than with the phosphate group [113-118]. The reaction between Ag and a GC (guanine-cytosine) base pair proceeds via two steps, whereas that between Ag" and an AT (adenine-thymine) base pair requires only one step [116], Ag appears to be attached to the N atom... 

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