Ionic strength Dotaz Zobrazit nápovědu
In this study, the apparent binding constants and limiting mobilities of the multiply charged complexes of the Δ- and Λ-enantiomers of Ru(II)- and Fe(II)-polypyridyl associates ([Ru(2,2'-bipyridine)3 ]2+ , [Ru(1,10-phenanthroline)3 ]2+ , and [Fe(1,10-phenanthroline)3 ]2+ ) with single-isomer 2,3-diacetylated-6-sulfated-cyclodextrins (CDs) (12Ac-6S-α-CD, 14Ac-7S-β-CD, and 16Ac-8S-γ-CD) were determined by ACE using uncorrected and ionic strength corrected actual mobilities of the species involved. Two limiting models were tested for the ionic strength correction of the actual mobilities based on an empirical relation for the ionic strength correction of multivalent ionic species. In model 1, the nominal values of the charge numbers (zS,nom ) and analytical concentrations (cS,nom ) of the above CD selectors in the BGEs were applied for calculation of the BGE ionic strength, as usual. In model 2, the CD selectors were considered as singly charged species (zS = -1) with |zS,nom |-times higher concentrations in the BGE than their analytical concentrations (cS = |zS,nom | × cS,nom ) in the calculation of the BGE ionic strength. In all three cases-with uncorrected actual mobilities as well as with actual mobilities corrected according to the two limiting models-the measured effective mobilities of the above enantiomers fit well the theoretical curves of their mobility dependences on the CD selectors concentrations in the BGE, with high average coefficients of determination (R2 = 0.9890-0.9995). Nevertheless, the best physico-chemically meaningful values of the apparent binding constants and the limiting mobilities of the enantiomer-CDs complexes with low RSDs were obtained using the actual mobilities of the species involved corrected according to model 2.
Albumin and hyaluronic acid are biodegradable, endogenous substances with potential use as drug carriers. These properties combined with the physical structure of the gel can lead to the formation of biologically active materials with application in medicine. This work investigated the gelation process of albumin solutions and mixed solutions of albumin and hyaluronan due to heating. The influence of the polymer concentration, weight ratio of hyaluronan and albumin, ionic strength, pH and molecular weight of hyaluronan is discussed. The study was carried out by measuring the rheological properties of the solutions, formed gels, and the gelation process. With increasing albumin concentration, the gel point was shifted towards lower temperature values. The resulting gels exhibited higher values of loss and storage moduli. For the mixed solutions of protein and polysaccharide, the effect of the polysaccharide concentration was observed. Based on the measurements, it can be assumed that the dependence of the complex modulus on the polysaccharide concentration has a peak at the certain hyaluronan: albumin weight ratio. The measured data showed, that increasing the ionic strength led to higher complex modulus values of the gels, and also to the increase of the temperature of the gel point. The gelation proceeded significantly faster when pH < pIBSA in comparison with the samples with pH > pIBSA. Increasing the pH of the solution (with respect to the albumin stability) led to higher complex modulus values of the gels formed. As a result of lowering the molecular weight of hyaluronan, the gel point was shifted towards lower temperature values, and resulting gels exhibited higher values of complex modulus. In addition, the ability of mixed BSA-HA solutions to bind hydrophobic substances was proven.
- MeSH
- hydrogely chemická syntéza chemie MeSH
- koncentrace vodíkových iontů MeSH
- kyselina hyaluronová chemie MeSH
- molekulová hmotnost MeSH
- osmolární koncentrace MeSH
- reologie MeSH
- sérový albumin hovězí chemie MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Progressive cerebral deposition of amyloid beta occurs in Alzheimers disease and during the aging of certain mammals (human, monkey, dog, bear, cow, cat) but not others (rat, mouse). It is possibly due to different amino acid sequences at positions 5, 10 and 13. To address this issue, we performed series of 100 ns long trajectories (each trajectory was run twice with different initial velocity distribution) on amyloid beta (1-42) with the human and rat amino acid sequence in three different environments: water with only counter ions, water with NaCl at a concentration of 0.15 M as a model of intracellular Na(+) concentration at steady state, and water with NaCl at a concentration of 0.30 M as a model of intracellular Na(+) concentration under stimulated conditions. We analyzed secondary structure stability, internal hydrogen bonds, and residual fluctuation. It was observed that the change in ionic strength affects the stability of internal hydrogen bonds. Increasing the ionic strength increases atomic fluctuation in the hydrophobic core of the human amyloid, and decreases the atomic fluctuation in the case of rat amyloid. The secondary structure analyses show a stable α-helix part between residues 10 and 20. However, C-terminus of investigated amyloids is much more flexible showing no stable secondary structure elements. Increasing ionic strength of the solvent leads to decreasing stability of the secondary structural elements. The difference in conformational behavior of the three amino acids at position 5, 10 and 13 for human and rat amyloids significantly changes the conformational behavior of the whole peptide.
- MeSH
- amyloidní beta-protein chemie MeSH
- chlorid sodný chemie MeSH
- hydrofobní a hydrofilní interakce MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- osmolární koncentrace MeSH
- peptidové fragmenty chemie MeSH
- povrchové vlastnosti MeSH
- sekundární struktura proteinů MeSH
- sekvence aminokyselin MeSH
- simulace molekulární dynamiky * MeSH
- stabilita proteinů MeSH
- terciární struktura proteinů MeSH
- voda chemie MeSH
- vodíková vazba MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- antitumorózní látky farmakologie chemie MeSH
- denaturace nukleových kyselin účinky léků MeSH
- DNA chemie účinky léků MeSH
- molekulární sekvence - údaje MeSH
- organoplatinové sloučeniny farmakologie chemie MeSH
- osmolární koncentrace MeSH
- sekvence nukleotidů MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
