Nucleic acids, in general

The interest in the interaction between metal ions and nucleic acids in general the finding on the antitumor... 

The dependence of the residual dipolar coupling on the angle that the vector forms with a reference axis explains why the use of dipolar couplings makes possible the determination of the relative orientation of different domains in a multidomain protein and facilitates nucleic acid structure determination. Dipolar couplings can constitute up to 50% of the total structural data available for nucleic acids, while this number drops to 10-15% in proteins. Thus, the impact of the use of dipolar couplings on the structure determination of nucleic acids is generally more substantial than in the case of proteins. Furthermore, the presence or absence of tertiary structure in a protein or nucleic acid does not have a major influence on the number of dipolar couplings that can be measured, in contrast to the case of the NOE. 

Lohse J, Dahl O, Neilsen PE (1999) Double duplex invasion by peptide nucleic acid a general principle for sequence-specific targeting of double stranded DNA. Proc Natl Acad Sci USA 96 11804-11808 Lonn U, Lonn S, Nylen U, Windblad G (1990) Bleomycin-induced DNA lesions are dependent on nucleosome repeat length. Biochem Pharmacol 39(1) 101-107 Lopez-Larraza DM, Bianchi NO (1993) DNA response to bleomycin in mammalian cells with variable degrees of chromatin condensation. Environ Mol Mutagen 21(3) 258—264 Lopez-Larraza DM, Padron J, Rond NE, Vidal Rioja LA (2006) Chromatin condensation and differential sensitivity of mammalian and insect cells to DNA strand breaks induced by bleomycin. Mutat Res 16 April [Epub ahead of print]... 

The arch for target(s) in vivo is practically insuperable. Thus, the only possible approach is to investi te in vitro eventual interactions of the drug with biological targets such as DNA, RNA, proteins and others. The first step of such in vitro studies consists in observing interactions with DNA, owing to the fact that this nucleic acid is generally considered as the most deeply involved in the intimate processes of life and death. This explains why we focused firstly our attention and efforts on the study of MYKO 63-DNA eventual interactions by two suitable techniques for this purpose, namely the Scatchard technique and Raman spectroscopy... 

Commercial surfactants are, in general, chemically impure and may contain varying amounts of water and additives. After prolonged storage of liquid nonionic surfactants the composition tend to change. It should be observed that even trace impurities might sometimes produce a bottleneck in carrying out spectroscopic studies of proteins/nucleic acids in RMs. In addition, the impurities may interfere with the behavior of biomolecules and also cause problems of reproducibility. To achieve reproducible results, it is advisable to purify the surfactants to be used whenever possible [121. 

G. Blackburn and M. Gait, Nucleic Acids in Chemistry and Biology (1991), Oxford University Press (New York). An excellent book on general aspects of nucleic acids. 

Figure 21.1 has been drawn to suggest that F+ > r. This inequality is generally true for nucleic acids in low to moderate salt, a phenomenon sometimes called the polyelectrolyte effect (Draper, 2008 Record and Richey, 1988). Any RNA conformational change that increases the density of phosphate charges will also increase T+ at the expense of T (Record et al., 1998). Flowever, T + may be similar to T at high salt concentrations for instance, T+ = 0.46 and T = —0.54 ions/nucleotide for DNA in 0.98 MNaBr (Strauss et al., 1967). 

Hershey, A. D. Chase, M. (1952). Independent functions of viral protein and nucleic acid in growth of bacteriophage. Journal of General Physiology, 36, 39-56. 

Lower nucleic acid concentrations are best determined fluorimetrically. These methods generally depend on the fact that certain dyes can bind to nucleic acids by intercalating between successive base pairs, and this binding is accompanied by marked increases in the fluorescence quantum yield. Ethidium bromide fluorescence (Aex 260-360 nm Af.rr] 560 nm), which is commonly used to visualise nucleic acids in gel electrophoresis, can also be used to quantitate double stranded DNA and RNA with a sensitivity of about 10 ng (Karsten and Wollenberger 1977). The dye 4,6-diamidino-2-phenylindole (DAPI) (Aex 360 nm 2f.m 450 nm) can be used to quantitate DNA specifically with a detection limit of about lng (Brunk et al. 1979). 

How do synthetases choose their tRNA partners This enormously important step is the point at which Translation" takes place—at which the correlation between the amino acid and the nucleic acid worlds is made. In a sense, aminoacyl-tRNA synthetases are the only molecules in biology that know" the genetic code. Their precise recognition of tRNAs is as important for high-fidelity protein synthesis as is the accurate selection of amino acids. In general, tRNA recognition by the synthetase is different for each synthetase and tRNA pair. Consequently, generalities are difficult to make. We will examine the interaction of two synthetases with their tRNA partners. 

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