Singlet molecular oxygen ((1)O2) contributes to protein damage triggering biophysical and biochemical changes that can be related with aging and oxidative stress. Serum albumins, such as bovine serum albumin (BSA), are abundant proteins in blood plasma with different biological functions. This paper presents a kinetic and spectroscopic study of the (1)O2-mediated oxidation of BSA using the tris(2,2'-bipyridine)ruthenium(II) cation [Ru(bpy)3](2+) as sensitizer. BSA quenches efficiently (1)O2 with a total (chemical+physical interaction) rate constant kt(BSA)=7.3(±0.4)×10(8)M(-1)s(-1), where the chemical pathway represented 37% of the interaction. This efficient quenching by BSA indicates the participation of several reactive residues. MALDI-TOF MS analysis of intact BSA confirmed that after oxidation by (1)O2, the mass protein increased the equivalent of 13 oxygen atoms. Time-resolved emission spectra analysis of BSA established that Trp residues were oxidized to N'-formylkynurenine, being the solvent-accessible W134 preferentially oxidized by (1)O2 as compared with the buried W213. MS confirmed oxidation of at least two Tyr residues to form dihydroxyphenylalanine, with a global reactivity towards (1)O2 six-times lower than for Trp residues. Despite the lack of MS evidences, kinetic and chemical analysis also suggested that residues other than Trp and Tyr, e.g. Met, must react with (1)O2. Modeling of the 3D-structure of BSA indicated that the oxidation pattern involves a random distribution of (1)O2 into BSA; allowing also the interaction of (1)O2 with buried residues by its diffusion from the bulk solvent through interconnected internal hydrophilic and hydrophobic grooves.
- MeSH
- 2,2'-dipyridyl analogy a deriváty farmakologie MeSH
- hydrofobní a hydrofilní interakce MeSH
- kinetika MeSH
- oxidace-redukce MeSH
- oxidační stres * MeSH
- sérový albumin hovězí chemie metabolismus MeSH
- singletový kyslík chemie metabolismus MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- stárnutí metabolismus patologie MeSH
- tryptofan chemie metabolismus MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
Titania nanofibers were fabricated using the industrial Nanospider(TM) technology. The preparative protocol was optimized by screening various precursor materials to get pure anatase nanofibers. Composite films were prepared by mixing a commercial paste of nanocrystalline anatase particles with the electrospun nanofibers, which were shortened by milling. The composite films were sensitized by Ru-bipyridine dye (coded C106) and the solar conversion efficiency was tested in a dye-sensitized solar cell filled with iodide-based electrolyte solution (coded Z960). The solar conversion efficiency of a solar cell with the optimized composite electrode (η = 7.53% at AM 1.5 irradiation) outperforms that of a solar cell with pure nanoparticle film (η = 5.44%). Still larger improvement was found for lower light intensities. At 10% sun illumination, the best composite electrode showed η = 7.04%, referenced to that of pure nanoparticle film (η = 4.69%). There are non-monotonic relations between the film's surface area, dye sorption capacity and solar performance of nanofiber-containing composite films, but the beneficial effect of the nanofiber morphology for enhancement of the solar efficiency has been demonstrated.
- MeSH
- 2,2'-dipyridyl analogy a deriváty chemie MeSH
- barvicí látky chemie MeSH
- elektrody MeSH
- elektrolyty chemie MeSH
- nanočástice chemie MeSH
- nanovlákna chemie ultrastruktura MeSH
- organokovové sloučeniny chemie MeSH
- polymery chemie MeSH
- sluneční energie * MeSH
- titan chemie MeSH
- zdroje elektrické energie * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The cytotoxicity of chloropolypyridyl ruthenium complexes of structural formulas [Ru(terpy)-(bpy)Cl]Cl, cis-[Ru(bpy)2Cl2], and mer-[Ru(terpy)Cl3] (terpy = 2,2':6'2"-terpyridine, bpy = 2,2'-bipyridyl) has been studied in murine and human tumor cell lines. The results show that mer-[Ru(terpy)Cl3] exhibits a remarkably higher cytotoxicity than the other complexes. Moreover, investigations of antitumor activity in a standard tumor screen have revealed the highest efficiency for mer-[Ru(terpy)Cl3]. In a cell-free medium, the ruthenium complexes coordinate to DNA preferentially at guanine residues. The resulting adducts can terminate DNA synthesis by thermostable VentR DNA polymerase. The reactivity of the complexes to DNA, their efficiency to unwind closed, negatively supercoiled DNA, and a sequence preference of their DNA adducts (studied by means of replication mapping) do not show a correlation with biological activity. On the other hand, the cytotoxic mer-[Ru(terpy)Cl3] exhibits a significant DNA interstrand cross-linking, in contrast to the inactive complexes which exhibit no such efficacy. The results point to a potential new class of metal-based antitumor compounds acting by a mechanism involving DNA interstrand cross-linking.
- MeSH
- 2,2'-dipyridyl * analogy a deriváty toxicita MeSH
- adukty DNA * MeSH
- antitumorózní látky farmakologie toxicita MeSH
- DNA-dependentní DNA-polymerasy metabolismus MeSH
- HeLa buňky MeSH
- konformace nukleové kyseliny MeSH
- leukemie L1210 MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- myši MeSH
- organokovové sloučeniny * toxicita MeSH
- reagencia zkříženě vázaná MeSH
- replikace DNA účinky léků MeSH
- sekvence nukleotidů MeSH
- superhelikální DNA účinky léků MeSH
- testy toxicity MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
- srovnávací studie MeSH
