Intercalation, in DNA

Satisfactory fits of the fluorescence decays for ethidium bound to yeast tRNAPhe and E. coli tRNA al require (at least) two exponentials in the sum response S(t) [cf. Eq. (4.56)] under all conditions studied.0 870 88) The normalized amplitudes and lifetimes for tRNA 1 (extrapolated to zero concentration) are S° = 0.917, r, = 25.6ns and S02 = 0.082, t2 = 5.6 ns.(187) The results for tRNAPhe are similar.(188) This requirement for two (or more) exponentials is unequivocal evidence for at least two ethidium binding sites. The dominant component has a lifetime similar to, but slightly longer than, that of ethidium intercalated in DNA and is taken to represent ethidium... 

LD spectra of A- and A-[Ru(phen)2(dppz)] " " intercalated in DNA are very different and this is rationalized in terms of deviations from the idealized intercalation geometry. LD spectroscopic data for intercalated meso-, A,A-, and A,A-[(phen)2Ru(/i-335)Ru(phen)2]" indicate that the Ru(phen)2(dppz)-like units bind in similar orientations to the mononuclear complexes. Formation of the intercalated species must involve threading of the [(phen)2Ru(u-335)Ru(phen)2]" complex through the DNA strands. " ... 

ACONITATE DECARBOXYASE ACONITATE A-ISOM ERASE Acridine dye intercalation in DNA, SCATCHARD PLOT ACROSIN AcA,... 

The induced CD of an electric dipole transition of a solute intercalated in DNA has been calculated using a matrix method and wavefunctions proposed for the transitions of... 

In light of the above bimolecular studies of static and dynamic Ru(II) -emission quenching by donors and acceptors intercalated in DNA, it is even more important to focus on the results of the tethered Ru/Rh-DNA duplex described above. The basic result is that Ru(II) -emission quenching is interpreted as... 

The correct choice = B. Tamoxifen binds to the estrogen receptor and acts as an antagonist. Doxorubicin intercalates in DNA and thus interferes in transcription. Cyclophosphamide, mechlorethamine and cisplatin can cross-link with DNA strands to inhibit its function. 

The stability of [Co(am)6]3+ complexes allows the template construction of tricyclic ligands around the metal ion. An example is the sarcophagine complex (17-F-I) in which the metal center is irreversibly encapsulated but retains its redox activity. With suitable substituents, such complexes can act as intercalators in DNA or as photosensitizers.14... 

A different kind of mutation is produced by flat aromatic molecules such as the acridines (Figure 27.44). These compounds intercalate in DNA—that is, they slip in between adjacent base pairs in the DNA double helix. 

Many recents studies have focused on applications of metallointerca-lation, which is also an important noncovalent interaction of metal complexes with nucleic acids. Intercalation is a common mode of association of small molecules with DNA, where a flat aromatic heterocyclic moiety inserts and stacks in between the DNA base pairs (13). Lippard and coworkers (14) determined in 1974 that platinum(II) complexes containing an aromatic heterocyclic ligand such as terpyridine could intercalate in DNA. Figure 2c shows such a stacking interaction of such a complex in a dinucleotide (15). Recently, we have found that intercalation is not restricted to completely flat, square planar complexes, but partial intercalation of ligands coordinated to octahedral metal centers is feasible as well... 

Initially, PET in DNA was studied using the electron donors and acceptors intercalated in DNA in a random manner. In 1992, Harriman and Brun reported fluorescence lifetimes of calf thymus DNA using ethidium bromide (EB+) and V,V -dimethyl-2,7-diazapyrenium dichloride (DAP +) as intercalators. They found the short fluorescence lifetime components to be due to PET between EB+ and DAP +. On the basis of the assumption that PET occurred between EB+ and DAP + separated by 3-5 base pairs, PET rates were estimated. Since the electron transfer rate ( et) can be expressed as a function of the donor-acceptor distance (r) in (7), the value was evaluated to be 0.88 a value close to that estimated for proteins. 

Very T, Despax S, Hebraud P, Monari A, Assfeld X (2012) Spectral properties of polypyridyl ruthenium complex intercalated in DNA theoretical insights on the surrounding effects for [Ru(dppz)(bpy)j2+. phys Chem Chem Phys 14 12496-12504... 

Quinine Intercalates in DNA helix Phenylalanine-ammonia lyase induced Pea pods Hadwiger and Swochaw (1971)... 

Figure 14. The structure of l-DNA The planar platinum complex [(bipy)Pt(en)] [21] readily intercalates in DNA. The saturated structure has the L (ladder) form in which the DNA helix is completely unwound and the intercalation appears to occur regularly in every third position (redrawn from [64]).

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