A spectroscopic study of poly(dA–dT)·poly(dA–dT) in microemulsions

Circular dichroism of polynucleotides: Interactions of NiCl2 with poly(dA‐dT)·poly(dA‐dT) and poly(dG‐dC)·poly(dG‐dC) in a water‐in‐oil microemulsion

“…The melting was indicated by hyperchromism in the UV band, and decreased amplitude and red-shift of the CD spectra, consequent to the loss of base-stacking and ordered double helical structure. Since complete melting could not be observed, the hyperchromic effect measured (5-10%) was much smaller than that observed for thermal denaturation in solution 34 or chemical denaturation in microemulsion, 45 that can be larger than 50%.…”

“…Such destabilizing effect is even more surprising when one considers that thermal melting of polyAT in micro- emulsion, in the absence of nickel, cannot be observed even at NaCl concentrations as low as 10.0 mM, where in aqueous solution melting occurs at 317.5 K. 34 However, even in microemulsion, when the observed temperature-induced transition is really melting, an increase of the nickel concentration leads to lower values of T m , in agreement with the literature reports on the effects of multivalent cations on polynucleotides in aqueous solution. 15,58 Consistent with the known behavior in aqueous solution is also the T m increase observed at increasing I, when the NiCl 2 concentration is kept constant (Table 1).…”

“…PolyGC (sodium salt, MW 5 490 7 520 kDa) was also a Sigma product and arrived in vials of 25 U. Lyophilized polyAT and polyGC samples were prepared in Eppendorf vials and stored over silica gel as previously described. 34 NaCl (Merck Suprapur) was dried at 383 K for 5 h in an oven and then stored over silica gel under vacuum.…”

“…300 mM) the confinement in the aqueous compartment of the lE favors the formation of condensed structures of the DNA model molecules similar to those obtained, for the natural polynucleotide, in the presence of high molecular weight polymers (C forms). 33,34 Recently, we have examined the thermal behavior of polyAT in aqueous solution in the presence of NiCl 2 . The melting temperature of the double helix to random coil transition increases with ionic strength at constant NiCl 2 concentration and decreases with Ni(II) concentration at constant ionic strength.…”

The novel hexadecyltrimethylammonium bromide (CTAB) based organogel as reactor for ester synthesis by entrapped Candida rugosa lipase

“…Remarkably, this kind of support represents a great improvement in the development of new tools to study the protein-surfactant interactions and, more interestingly, from a biotechnological point of view, it could allow the encapsulation of negatively charged hosts, like nucleic acid [14] and protein.…”