Surface-enhanced raman spectroscopy investigation of fluoroquinolones-DNA-DNA gyrase-Mg2+ interactions. II. Interaction of pefloxacin with Mg2+ and DNA

✍ Scribed by S. Lecomte; M.-H. Baron

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 379 KB
• Volume: 3
• Category: Article
• ISSN: 1075-4261
• DOI: 10.1002/(sici)1520-6343(1997)3:1<31::aid-bspy3>3.0.co;2-v

✦ Synopsis

The interactions between pefloxacin (antimicrobial agent), magnesium, and DNA single or double strand are studied by UV/Vis and surface-enhanced Raman spectroscopies at biological active concentrations: pefloxacin 2 1 10 06 , DNA 2 1 10 05 , and Mg 2/ 10 03 M. Pefloxacin interacts with Mg 2/ via its carboxylate and pyridinone C4|O groups. In presence of the colloid, with nitrate salts, Mg 2/ is positioned near the C4|O and the drug is bound to the Ag surface via the carboxylate. The conjugated rings are tilted over the colloidal particles and a charge transfer from the plasmon of the surface to the pefloxacin occurs, as in absence of salts or in presence of sodium nitrate. With MgCl 2 , pefloxacin/Mg 2/ species are also adsorbed onto the colloid but essentially via the C4|O of the pyridinone ring, the carboxylate being partly bound to Mg 2/ . The charge transfer is canceled as occurring with NaCl. Magnesium interacts with DNA single or double strand via the phosphodiester groups and amino bases are oriented toward the colloidal surface. Chlorides specifically favor the fixation of the adenine NH 2 substituent. At low DNA concentration and in presence of Mg 2/ , the adsorbed bases are tilted over the Ag surface, more for double-than for single-strand DNA. Ternary pefloxacin-Mg 2/ -DNA complexes are adsorbed onto the silver surface, via the amino group of the DNA bases and via one carboxylate oxygen of the drug. The ternary complex formed with Mg 2/ (nitrate) and DNA modifies the charge transfer from the plasmon of the surface to the drug.