Tuning Net Charge in Aliphatic Polycarbonates Alters Solubility and Protein Complexation Behavior
Ontology highlight
ABSTRACT:
SUBMITTER: Posey N
PROVIDER: S-EPMC8427630 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Almost all commercial proteins are purified using ammonium sulfate precipitation. Protein-polymer conjugates are synthesized from pure starting materials, and the struggle to separate conjugates from polymer, native protein, and from isomers has vexed scientists for decades. We have discovered that covalent polymer attachment has a transformational effect on protein solubility in salt solutions. Here, protein-polymer conjugates with a variety of polymers, grafting densities, and polymer lengths are generated using atom transfer radical polymerization. Charged polymers increase conjugate solubility in ammonium sulfate and completely prevent precipitation even at 100% saturation. Atomistic molecular dynamic simulations show the impact is driven by an anti-polyelectrolyte effect from zwitterionic polymers. Uncharged polymers exhibit polymer length-dependent decreased solubility. The differences in salting-out are then used to simply purify mixtures of conjugates and native proteins into single species. Increasing protein solubility in salt solutions through polymer conjugation could lead to many new applications of protein-polymer conjugates.
| S-EPMC6797786 | biostudies-literature
Project description:Protein solubility is a problem for many protein chemists, including structural biologists and developers of protein pharmaceuticals. Knowledge about how intrinsic factors influence solubility is limited due to the difficulty of obtaining quantitative solubility measurements. Solubility measurements in buffer alone are difficult to reproduce, because gels or supersaturated solutions often form, making it impossible to determine solubility values for many proteins. Protein precipitants can be used to obtain comparative solubility measurements and, in some cases, estimations of solubility in buffer alone. Protein precipitants fall into three broad classes: salts, long-chain polymers, and organic solvents. Here, we compare the use of representatives from two classes of precipitants, ammonium sulfate and polyethylene glycol 8000, by measuring the solubility of seven proteins. We find that increased negative surface charge correlates strongly with increased protein solubility and may be due to strong binding of water by the acidic amino acids. We also find that the solubility results obtained for the two different precipitants agree closely with each other, suggesting that the two precipitants probe similar properties that are relevant to solubility in buffer alone.
| S-EPMC3328702 | biostudies-literature
Project description:Dystrophia myotonica type 1 (DM1) results from nuclear sequestration of splicing factors by a messenger RNA (mRNA) harboring a large (CUG) n repeat array transcribed from the causal (CTG) n DNA amplification. Several compounds were previously shown to bind the (CUG) n RNA and release the splicing factors. We now investigated for the first time the interaction of an aliphatic polycarbonate carrying guanidinium functions to DM1 DNA/RNA model probes by affinity capillary electrophoresis. The apparent association constants (K a) were in the range described for reference compounds such as pentamidine. Further macromolecular engineering could improve association specificity. The polymer presented no toxicity in cell culture at concentrations of 1.6-100.0 ?g/mL as evaluated both by MTT and real-time monitoring xCELLigence method. These promising results may lay the foundation for a new branch of potential therapeutic agents for DM1.
| S-EPMC6843715 | biostudies-literature
Project description:The complexation abilities of five cyclodextrins (CDs) with seven phenylpropanoids (PPs) were evaluated by UV-visible spectroscopy, phase solubility studies and molecular modeling. Formation constants (K f), complexation efficiency (CE), PP:CD molar ratio, increase in formulation bulk and complexation energy were assessed. All complexes exhibited a 1:1 stoichiometry but their stability was influenced by the nature and the position of the phenyl ring substituents. A relationship between the intrinsic solubility of guests (S 0) and the solubilizing potential of CD was proposed. Molecular modeling was used to investigate the complementarities between host and guest. Finally, the antioxidant activity of encapsulated PPs was evaluated by scavenging of the stable DPPH radical.
| S-EPMC4187030 | biostudies-literature
Project description:Different types of surface forces, acting in the films of pentane, hexane, and heptane on water are discussed. It is shown that an important contribution to the surface forces originates from the solubility of water in alkanes. The equations for the distribution of electric potential inside the film are derived within the Debye-Hückel approximation, taking into account the polarization of the film boundaries by discrete charges at water-alkane interface and by the dipoles of water molecules dissolved in the film. On the basis of above equations we estimate the image charge contribution to the surface forces, excess free energy, isotherms of water adsorption in alkane film, and the total isotherms of disjoining pressure in alkane film. The results indicate the essential influence of water/alkane interface charging on the disjoining pressure in alkane films, and the wettability of water surface by different alkanes is discussed.
| S-EPMC5456670 | biostudies-other
Project description:Solutions with high pH values are sometimes thought to contain net negative charge because of an excess of OH- groups, while solutions with low pH values are thought opposite. To follow up on these speculations, we used a simple electrochemical cell to study three types of solution: electrolyzed waters with differing pH values; acids and bases with different pH values; and various salt solutions. When electrolyzed waters of various pH values were tested against water of pH 7, we found that acidic waters were indeed positively charged, while basic waters were negatively charged. We found much the same when standard acids and bases were compared to reference solutions: acidic solutions were positively charged while basic solutions were negatively charged. Various salts, including NaCl, KCl, Na2SO4, and K2SO4, were also tested against DI water (containing trace amounts of NaCl to lend conductivity). Surprisingly, all salts were found to be negatively charged, more so as their concentrations increased. This collection of results supports the hypothesis that at least some aqueous solutions may contain net charge.
| S-EPMC9612516 | biostudies-literature
Project description:Through charge-driven interfacial complexation, we produced millimeter-sized spheroidal hydrogels (SH) with a core-shell structure allowing long-term stability in aqueous media. The SH were fabricated by extruding, dropwise, a cationic cellulose nanofibril (CCNF) dispersion into an oppositely charged poly(acrylic acid) (PAA) bath. The SH have a solid-like CCNF-PAA shell, acting as a semipermeable membrane, and a liquid-like CCNF suspension in the core. Swelling behavior of the SH was dependent on the osmotic pressure of the aging media. Swelling could be suppressed by increasing the ionic strength of the media as this enhanced interfibrillar interactions and thus strengthened the outer gel membrane. We further validated a potential application of SH as reusable matrixes for glucose oxidase (GOx) entrapment, where the SH work as microreactors from which substrate and product are freely able to migrate through the SH shell while avoiding enzyme leakage.
| S-EPMC7147256 | biostudies-literature
Project description:Interference features in the transmission spectra can dominate charge transport in metal-molecule-metal junctions when they occur close to the contact Fermi energy (E F). Here, we show that by forming a charge-transfer complex with tetracyanoethylene (TCNE) we can introduce new constructive interference features in the transmission profile of electron-rich, thiophene-based molecular wires that almost coincide with E F. Complexation can result in a large enhancement of junction conductance, with very efficient charge transport even at relatively large molecular lengths. For instance, we report a conductance of 10-3 G 0 (∼78 nS) for the ∼2 nm long α-quaterthiophene:TCNE complex, almost two orders of magnitude higher than the conductance of the bare molecular wire. As the conductance of the complexes is remarkably independent of features such as the molecular backbone and the nature of the contacts to the electrodes, our results strongly suggest that the interference features are consistently pinned near to the Fermi energy of the metallic leads. Theoretical studies indicate that the semi-occupied nature of the charge-transfer orbital is not only important in giving rise to the latter effect, but also could result in spin-dependent transport for the charge-transfer complexes. These results therefore present a simple yet effective way to increase charge transport efficiency in long and poorly conductive molecular wires, with important repercussions in single-entity thermoelectronics and spintronics.
| S-EPMC6385675 | biostudies-literature
Project description:Intricate processes in the thymus and periphery help curb the development and activation of autoreactive T cells. The subtle signals that govern these processes are an area of great interest, but tuning TCR sensitivity for the purpose of affecting T cell behavior remains technically challenging. Previously, our laboratory described the derivation of two TCR-transgenic CD4 T cell mouse lines, LLO56 and LLO118, which recognize the same cognate Listeria epitope with the same affinity. Despite the similarity of the two TCRs, LLO56 cells respond poorly in a primary infection whereas LLO118 cells respond robustly. Phenotypic examination of both lines revealed a substantial difference in their surface of expression of CD5, which serves as a dependable readout of the self-reactivity of a cell. We hypothesized that the increased interaction with self by the CD5-high LLO56 was mediated through TCR signaling, and was involved in the characteristic weak primary response of LLO56 to infection. To explore this issue, we generated an inducible knock-in mouse expressing the self-sensitizing voltage-gated sodium channel Scn5a. Overexpression of Scn5a in peripheral T cells via the CD4-Cre promoter resulted in increased TCR-proximal signaling. Further, Scn5a-expressing LLO118 cells, after transfer into BL6 recipient mice, displayed an impaired response during infection relative to wild-type LLO118 cells. In this way, we were able to demonstrate that tuning of TCR sensitivity to self can be used to alter in vivo immune responses. Overall, these studies highlight the critical relationship between TCR-self-pMHC interaction and an immune response to infection.
| S-EPMC5940509 | biostudies-literature
Project description:We studied the effect of several CDs on carvedilol's solubility and chemical stability in various aqueous media. Our present results show that it is possible to achieve a carvedilol concentration of 5 mg/mL (12.3 mM) in the presence of 5 eq of γCD or RAMEB in an aqueous medium with an acceptable acid pH (between 3.5 and 4.7). Carvedilol formed 1:1 inclusion complexes but those with RAMEB appear to be stronger (K = 317 M-1 at 298 K) than that with γCD (K = 225 M-1 at 298 K). The complexation of carvedilol by RAMEB significantly increased the drug's photochemical stability in aqueous solution. These results might constitute a first step towards the development of a novel oral formulation of carvedilol.
| S-EPMC8620534 | biostudies-literature