Bases nucleic acids

These relationships are general Hydroxyl substituted purines and pyrimidines exist in their keto forms ammo substituted ones retain structures with an ammo group on the ring The pyrimidine and punne bases m DNA and RNA listed m Table 28 1 follow this general rule Beginning m Section 28 7 we 11 see how critical it is that we know the cor rect tautomeric forms of the nucleic acid bases... 

Even if It could be shown that RNA preceded both DNA and proteins in the march toward living things that doesn t automatically make RNA the first self replicating molecule Another possibility is that a self replicating polynucleotide based on some carbo hydrate other than o ribose was a precursor to RNA Over many generations natural selection could have led to the replacement of the other carbohydrate by D ribose giving RNA Recent research on unnatural polynucleotides by Professor Albert Eschenmoser of the Swiss Federal Institute of Technology (Zurich) has shown for example that nucleic acids based on L threose possess many of the properties of RNA and DNA... 

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). 

Significant progress in the optimization of VDW parameters was associated with the development of the OPLS force field [53]. In those efforts the approach of using Monte Carlo calculations on pure solvents to compute heats of vaporization and molecular volumes and then using that information to refine the VDW parameters was first developed and applied. Subsequently, developers of other force fields have used this same approach for optimization of biomolecular force fields [20,21]. Van der Waals parameters may also be optimized based on calculated heats of sublimation of crystals [68], as has been done for the optimization of some of the VDW parameters in the nucleic acid bases [18]. Alternative approaches to optimizing VDW parameters have been based primarily on the use of QM data. Quantum mechanical data contains detailed information on the electron distribution around a molecule, which, in principle, should be useful for the optimization of VDW... 

The Npeoc group was introduced for protection of the exocyclic amino functions of nucleic acid bases, but has also been used for simple amines. 

One of the lines of approach of such an investigation is the study of analogs of nucleic acid bases. The objective here is to prepare such analogs as would be incorporated into the nucleic acid molecules on the basis of their similarity to the natural species or as could interfere at some of the steps of nucleic acid biosynthesis. 

The 8-aza analogs of purine bases were the first to be studied among all the aza analogs of nucleic acid bases (as early as 1945). Before that time the chemistry of these substances had not been treated in detail from any aspect. Thus the entire chemistry of the u-triazolo [4,5-d]pyrimidines was developed only in connection with the study of antimetabolites of nucleic acid components. Therefore all the papers involved are largely of preparative character and only rarely discuss. theoretical points. 

Solute-solvent interactions in aqueous solutions of pyrimidine nucleic acid bases 99PAC1286. 

Anionic Polyelectrolytes Containing Nucleic Acid Bases.136... 

Neutral Water-Soluble Polymers Containing Nucleic Acid Bases. . . . 143... 

Ionic Surfactants Containing Nucleic Acid Bases.146... 

Kinoshita, Imoto etal.11 14) synthesized other anionic models, 5 (APVP), CPVP, UPVP, TPVA, HPVA, THPVA, and 6 (AMPPVA), by the polymer reaction of N-eoupled(2-dihydrogenphosphate)-ethylderivatives of nucleic acid bases (or adenosine-5 -phosphate, AMP) with polyvinylaleohol. A, C, U, T, H, and TH denote adenine, cytosine, uracil, thymin, hypoxanthine, and theophylline, respectively. The authors reported the apparent hypochromities of 3 to 16% for many kinds of mixtures of the models and DNA or RNA, as compiled in Table 1. However, for the mixtures APVA + RNA, HPVA + RNA HPVA + DNA, THPVA + RNA, CPVA + DNA and CPVA + RNA, no hypochromicity was detected. 

It can be seen from the figure that the electrostatic repulsive forces between the macrocations are overwhelmed, probably by hydrophobic attractive forces between their hydrophobic side groups. It should be noted that the complimentary base-base pairing is unimportant in the present case. If this is not the case, the mixtures of APVP and TPVP should show the largest hypochromicity. This, however, is not the case. The importance of the hydrophobic interactions between nucleic acid bases has been proposed by Ts o et al.I9 from thermodynamic parameters of various nucleic acid bases or nucleosides in aqueous media. 

UPEI), and poly[l-(uridin-5 -yl)-iminoethylene halide], 13 (UPEI ). They were obtained by quaternization of poly-4-vinylpyridine or polyethylenimine with ehlo-roethylated, ehloropropylated, or ehlorated nucleic acid bases. 

A hypochromicity was observed between THPVP and APVP (or TPVP). Since theophylline is not a nucleic acid base and does not form hydrogen-bonding, these observations indicate that stacking-type hydrophobic forces are important. 

Neutral Water-Soluble Polymers Containing Nucleic Acid Bases... 

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. 

Nucleic Acids-Based Therapeutics in the Battle Against Pathogenic Viruses... 

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