Nucleic acid base complexes

Nucleic Acid Base Complexes Elucidation of the Physical Origins of Their Stability... 

Because of the efficiency, the density functional theory also became an object of interest for the purpose of evaluation of intermolecular interaction energies for nucleic acid base complexes. Most standard functionals provide qualitatively a good picture of interactions in H-bonded nucleic acid base pairs. However, they completely fail for stacked complexes. This is due to the inability of current functionals to describe correctly the dispersion energy. Several routes were proposed to alleviate this deficiency with different rates of success [9-12],... 

The Nature of Interactions in Nucleic Acid Base Complexes... 

Fig. 20.1 The average, the maximal and the minimal values of intermolecular interaction energy for stacked nucleic acid base complexes calculated at the MP2/aug-cc-pVDZ level of theory...

In this article, we discussed several rigorous ab initio studies, including our own findings, which had recently put the discussion of the nature of intermolecular interactions in nucleic acid base complexes on quantitative basis. The results of computations summarized herein confirm that H-bonded and stacked base pairs are mainly stabilized by electrostatic/delocalization components and dispersion... 

Platinum—polyethyleneimine complexes prevent the division of bacteria, and are being tested as carriers in the treatment of cancer and vimses (445—447). Encapsulated PEIs containing nucleic acid bases activate the neutrophils in human blood (448). 

Poly A form a complex with a 4 1 stoichiometry. The apparent hypochromicities of various mixtures are listed in Table 4. The mixtures of A12 with Poly U and of T12 with Poly A showed large hypochromicities compared with other mixtures, which suggests the importance of the hydrogen-bonding formation between complementary nucleic acid bases such as A-U and T-A. 

Santamaria, R., Charro, E., Zacarias, A., Castro, M., 1999, Vibrational Spectra of Nucleic Acid Bases and Their Watson-Crick Pair Complexes , J. Comput. Chem., 20, 511. 

Sheina GG, Radchenko ED, Blagoi YP, Verkin BI (1978) Charge-transfer complexes of nucleic acid bases. Dokl Akad Nauk SSSR 240 463 66... 

Relatively few simple pyrimidine monomers have been incorporated into heterocyclic polymers (70MI11100). By far the greatest efforts with this ring system have involved polymerizable derivatives of nucleic acid bases and related compounds (81MH1102). The majority of this work has involved the synthesis and free radical polymerization of suitable vinyl- and acrylic-functional monomers, e.g. (134)-(136), although epoxy and other derivatives have also been studied. A number of the polymers exhibit base-paired complex formation with natural nucleic acid polymers or synthetic analogues, have found use in... 

Heavier metal ions and metal complexes can find sites on nitrogen atoms of the nucleic acid bases. Examples are the platinum complex cisplatin and the DNA-cleaving antibiotic neocarzinostatin (Box 5-B). Can metals interact with the n electrons of stacked DNA bases A surprising result has been reported for intercalating complexes of ruthenium (Ru) and rhodium (Rh). Apparent transfer of electrons between Ru (II) and Rh (III) over distances in excess of 4.0 nm, presumably through the stacked bases, has been observed,181 as has electron transfer from other ions.181a Stacked bases are apparently semiconductors.182... 

The sequences of all three pieces of RNA in the E. coli ribosomes are known as are those from many other species. These include eukaryotic mitochondrial, plas-tid, and cytosolic rRNA. From the sequences alone, it was clear that these long molecules could fold into a complex series of hairpin loops resembling those in tRNA. For example, the 16S rRNA of E. coli can fold as in Fig. 29-2A and eukaryotic 18S RNA in a similar way (Fig. 29-4).38/39/67 69 The actual secondary structures of 16S and 18S RNAs, within the folded molecules revealed by X-ray crystallography, are very similar to that shown in Fig. 29-2A. Ribosomal RNAs undergo many posttranscriptional alterations. Methylation of 2 -hydroxyls and of the nucleic acid bases as well as conversion to pseudouridines (pp. 1638-1641) predominate over 200 modifications, principally in functionally important locations that have been found in human rRNA.69a... 

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