Conformational changes in the DNA molecule in solution caused by the binding of a light-sensitive cationic surfactant

The photosensitive azobenzene-containing surfactant C 4 -Azo-OC 6 TMAB is a promising agent for reversible DNA packaging in a solution. The simulation of the trans-isomer surfactant organization into associates in a solution with and without salt as well as its binding to DNA at different NaCl concentrations was carried out by molecular dynamics. Experimental data obtained by spectral and hydrodynamic methods were used to verify the results of simulation. It was shown that head-to-tail aggregates with close to antiparallel orientation of surfactant molecules were formed at certain NaCl and surfactant concentrations (below critical micelle concentration). Such aggregates have two positively charged ends, and therefore, they can be attracted to negatively charged DNA phosphates far located along the chain, as well as those that belong to different molecules. This contributes to the formation of intermolecular DNA–DNA contacts, and this way, the experimentally observed precipitation of DNA can be explained.

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“…DNA interaction with the surfactant in solutions at high salt concentrations (>0.5 M NaCl) was not observed. 7 , 8 , 16 …”

Section: Resultsmentioning

confidence: 99%

“…At a high salt concentration (>0.5 M NaCl), the surfactant does not induce DNA shrinkage and DNA condensation. 7 , 16 …”

Section: Introductionmentioning

confidence: 99%

Some Features of Surfactant Organization in DNA Solutions at Various NaCl Concentrations

et al. 2020

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“…The structure and basic properties of azobenzene trimethylammonium bromide (AzoTAB), M = 476 g/mol, have been described in recent works [ 5 , 11 , 25 , 30 ].…”

Section: Methodsmentioning

confidence: 99%

“…In our research, the cationic azobenzene trimethylammonium bromide surfactant C 4 -Azo-OC 6 TMAB, AzoTAB ( Figure 1 ) was used. It was observed that at low ionic strength the DNA shrinkage induced by AzoTAB is accompanied by the change in DNA persistence length [ 5 , 25 ]. The DNA persistence length does not decrease as a result of phosphates screening at [NaCl] > 0.005 M NaCl [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

DNA Interaction with Head-to-Tail Associates of Cationic Surfactants Prevents Formation of Compact Particles

et al. 2018

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Cationic azobenzene-containing surfactants are capable of condensing DNA in solution with formation of nanosized particles that can be employed in gene delivery. The ratio of surfactant/DNA concentration and solution ionic strength determines the result of DNA-surfactant interaction: Complexes with a micelle-like surfactant associates on DNA, which induces DNA shrinkage, DNA precipitation or DNA condensation with the emergence of nanosized particles. UV and fluorescence spectroscopy, low gradient viscometry and flow birefringence methods were employed to investigate DNA-surfactant and surfactant-surfactant interaction at different NaCl concentrations, [NaCl]. It was observed that [NaCl] (or the Debye screening radius) determines the surfactant-surfactant interaction in solutions without DNA. Monomers, micelles and non-micellar associates of azobenzene-containing surfactants with head-to-tail orientation of molecules were distinguished due to the features of their absorption spectra. The novel data enabled us to conclude that exactly the type of associates (together with the concentration of components) determines the result of DNA-surfactant interaction. Predomination of head-to-tail associates at 0.01 M < [NaCl] < 0.5 M induces DNA aggregation and in some cases DNA precipitation. High NaCl concentration (higher than 0.8 M) prevents electrostatic attraction of surfactants to DNA phosphates for complex formation. DAPI dye luminescence in solutions with DNA-surfactant complexes shows that surfactant tails overlap the DNA minor groove. The addition of di- and trivalent metal ions before and after the surfactant binding to DNA indicate that the bound surfactant molecules are located on DNA in islets.

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“…The photoswitching of azobenzene based micelles has been found to be highly reversible but can be suppressed in aggregates precipitated from the solution. 28 Azobenzene derivatives have been used as surfactants bound to DNA to induce and control conformational changes 29,30 to get insight into a stabilization of RNA and DNA hairpins. 31−33 Bockmann et al developed an atomistic force field for a compound 34 which has been used to achieve photoisomerization driven peptide folding.…”

Section: ■ Introductionmentioning

confidence: 99%

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Knippenberg

Osella

2020

J. Phys. Chem. C

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The specific relationship between the alkyl tail lengths of four azobenzene probes embedded in DOPC liquid disorder membrane and their (non) linear optical (NLO) properties have been considered in the current study. Using extensive molecular dynamics calculations, the push/pull effect of the alkyl tails on the position and orientation of the probes in the model membrane are discussed. The simulations indicate that with increasing tail lengths the cis isomers are pushed closer to the membrane surface, while the trans ones are rather pulled toward the membrane center. Throughout hybrid quantum mechanics/molecular mechanics calculations, the linear and nonlinear optical properties of these compounds have been investigated. The pushing effect of the tails for cis azobenzene is translated in strong responses in the (non) linear optical spectroscopies, while the opposite is seen for the trans isomers. The cis isomer can be seen as the active state of the azobenzene compound for membrane recognition. The current work highlights the correlation between the tails of photosensitive membrane probes and their NLO properties, and focuses on unexpected behaviors of azobenzene derivatives in biological environments which can be exploited in distinguishing between soft and stiff cellular compartments that are of utmost importance for ion carrier transport.

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Conformational changes in the DNA molecule in solution caused by the binding of a light-sensitive cationic surfactant

Cited by 6 publications

References 16 publications

Some Features of Surfactant Organization in DNA Solutions at Various NaCl Concentrations

Some Features of Surfactant Organization in DNA Solutions at Various NaCl Concentrations

DNA Interaction with Head-to-Tail Associates of Cationic Surfactants Prevents Formation of Compact Particles

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

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