Potentiometric and spectrophotometric pH-titrations of the lesinurad for three consecutive dissociation constants determination were compared. Lesinurad is a selective inhibitor of uric acid reabsorption as part of a combination of medicines to treat high levels of uric acid in blood, also called hyperuricemia. Nonlinear regression of the pH-spectra with REACTLAB and SQUAD84 and of the pH-titration curve with ESAB determined three multiple close dissociation constants. The protonation scheme of lesinurad was suggested. A sparingly soluble anion L- of lesinurad was protonated to the still soluble species LH, LH2+ and LH32+ in pure water. Three consecutive thermodynamic dissociation constants were estimated pKTa1 = 2.09, pKTa2 = 4.25, pKTa3 = 6.58 at 25 °C and pKTa1 = 1.96, pKTa2 = 4.16, pKTa3 = 6.32 at 37 °C by UV-metric spectra analysis. The graph of molar absorption coefficients shows that the spectrum of species LH2+ and LH vary in colour, while protonation of chromophore LH2+ to LH32+ has less influence on chromophores in the lesinurad molecule. Three multiple thermodynamic dissociation constants of 1 × 10-4 M lesinurad were determined by the pH-metric analysis pKTa1 = 2.39, pKTa2 = 3.47, pKTa3 = 6.17 at 25 °C and pKTa1 = 2.08, pKTa2 = 3.29, pKTa3 = 6.03 at 37 °C. The values of enthalpy ΔH0(pKa1) = 19.19 kJ mol-1, ΔH0(pKa2) = 13.29 kJ mol-1, ΔH0(pKa3) = 38.39 kJ mol-1, show the dissociation process is endothermic. The positive values of ΔG0(pKa1) = 11.93 kJ mol-1, ΔG0(pKa2) = 24.26 kJ mol-1, ΔG0(pKa3) = 37.56 kJ mol-1 at 25 °C indicate that the dissociation process of pKa2 is not spontaneous, which was confirmed by its value of entropy ΔS0(pKa1) = 24.37 J mol-1, ΔS0(pKa2) = -36.79 J mol-1, ΔS0(pKa3) = 2.79 J mol-1. Three macro-dissociation constants of lesinurad and protonation locations were predicted by MARVIN and ACD/Percepta.
- MeSH
- chemie farmaceutická MeSH
- koncentrace vodíkových iontů MeSH
- potenciometrie přístrojové vybavení metody MeSH
- spektrofotometrie ultrafialová přístrojové vybavení metody MeSH
- termodynamika * MeSH
- thioglykoláty chemie MeSH
- triazoly chemie MeSH
- urikosurika chemie MeSH
- Publikační typ
- časopisecké články MeSH
Nanoparticle-protein conjugates have potential for numerous applications due to the combination of the properties of both components. In this paper we studied the conjugation of horse heart cytochrome c with ZnO nanoparticles modified by mercaptoacetic acid (MAA) which may be a material with great potential in anticancer therapy as a consequence of synergic effect of both components. Cyt c adsorption to the ZnO-MAA NPs surface was studied by UV-vis spectroscopy and by a dynamic light scattering in various pH. The results indicate that the optimal pH for the association of protein with modified nanoparticles is in range 5.8-8.5 where 90-96% of cytochrome c was assembled on ZnO-MAA nanoparticles. The interaction of proteins with nanoparticles often results in denaturation or loss of protein function. Our observations from UV-vis spectroscopy and circular dichroism performed preserved protein structure after the interaction with modified nanoparticles.
- MeSH
- adsorpce MeSH
- cirkulární dichroismus MeSH
- cytochromy c chemie MeSH
- imobilizované proteiny chemie MeSH
- koncentrace vodíkových iontů MeSH
- koně MeSH
- mikroskopie atomárních sil MeSH
- myokard chemie MeSH
- nanočástice chemie ultrastruktura MeSH
- oxid zinečnatý chemie MeSH
- spektrofotometrie MeSH
- thioglykoláty chemie MeSH
- velikost částic MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- lidé MeSH
- thioglykoláty farmakologie chemie terapeutické užití MeSH
- vlasy, chlupy MeSH
- Check Tag
- lidé MeSH
