SEC Analysis Research Articles

Controlled Ring-Opening Polymerization of Methyl Glycolide with Bifunctional Organocatalyst.

A bifunctional thiourea-amine-based organocatalyst (Takemoto's catalyst), employing a metal-free approach, is presented for the regioselective ring-opening polymerization (ROP) of optically active (D and L) methyl glycolide (MG). In this study, a chiral version of Takemoto's catalyst efficiently promotes the ROP of MG at room temperature, yielding poly(lactic-co-glycolic acids) (PLGAs) with predicted molecular weights and narrow polydispersity indices (PDI≤1.2). These PLGAs exhibit highly alternating structures without transesterification, as confirmed by 1H NMR, SEC, and MALDI-TOF analyses. Additionally, various macromolecular architectures, including linear and star-shaped PLGAs, were successfully synthesized using the corresponding multi-functional alcohol initiators while maintaining the same alternating structures and regioselectivity with PLGA obtained from benzyl alcohol as initiator. Computational studies were conducted to elucidate the mechanism of alternating PLGA formation, revealing two key transition states (TSs): TS-1, which implicates the nucleophilic attack of the hydroxyl group of the initiator or propagating chain on the carbonyl carbon of MG, and TS-2, which involves the subsequent ring-opening of the cyclic ester. The results indicate that ring-opening occurs at both the glycolyl and lactyl sites, with a preference for the glycolyl site, as supported by experimental results. The resulting atactic PLGAs are amorphous, rendering them suitable for drug delivery applications.

Oil palm frond leaves (OPFLs), a high recalcitrant biomass as an alternative cellulose source for glucose conversion

Among the oil palm biomass, oil palm frond leaves (OPFLs) are under-valued since they can be classified as a high recalcitrance feedstock due to the high lignin and hemicellulose content. This work proposes a new way of using OPFLs as alternative cellulose sources for glucose conversion by an application of various pre-treatments at varying parameters. From green pre-treatment, steam explosion (SE) is much more effective in disrupting the OPFLs structure in contrast to hydrothermal (HT) pre-treatment, by a vast dissolution of hemicellulose and depolymerization of lignin. The pre-impregnation with H2SO4 prior to steam explosion was beneficial to enhance the hemicellulose removal up to 89.94 %. The 2D-HSQC NMR analysis divulged the reduction of ß-O-4 linkage and S/G value after the SE and HT pre-treatment, verifying the degradation of lignin-carbohydrate linkage in OPFLs. Meanwhile, the dilute NaOH pre-treatment enhanced the delignification by 87.14 %. SEM analysis revealed a well-disrupted structure of pre-treated OPFLs exposing a higher cellulosic fraction, whereas SEC analysis divulged a decreasing pattern of degree of polymerization of cellulose. The enzymatic analysis revealed that pre-treated OPFLs yielded higher glucose ranging from 29.81 % to 49.98 % w/w, which was ∼3-fold higher than raw OPFLs (14.31 % w/w). A maximum cellulose digestibility (100 %) was achieved by steam-exploded OPFLs after 72 h of enzymatic hydrolysis. This suggests the potency of various pre-treatments to enhance enzymatic saccharification of OPFLs producing a higher glucose yield.

A novel cataract-related mutation R10P in γA-crystallin increases susceptibility to thermal shock and ultraviolet radiation of γA-crystallin

Congenital cataract is one of the most common causes of childhood blindness, typically resulting from genetic mutations. Over a hundred gene mutations associated with congenital cataract have been identified, with approximately half occurring in the Crystallin genes. In this study, we identified a novel γA-crystallin pathogenic mutation (c. 29G > C, p. Arg10Pro (R10P)), from a four-generation Chinese family with congenital cataract, and investigated its potential molecular mechanisms underlying congenital cataracts. We compared the protein structure and stability of purified the wild type (WT) and R10P under physiological conditions and environmental stresses (UV irradiation, pH imbalance, heat shock, and chemical denaturation) using spectroscopic experiments, SEC analysis, and the UNcle protein analysis system. The results demonstrate that γA-R10P has no significant impact on the structure of γA-crystallin on normal condition. However, it is more sensitive to UV irradiation at high concentrations and prone to aggregation at high temperatures. Therefore, our study reveals the crucial role of the conserved site mutation R10P in maintaining protein structure and stability, providing new insights into the mechanisms of cataract formation.

Biodegradable and biocompatible nonisocyanate polyurethanes synthesized from bio-derived precursors

Despite the enormous use of polyurethanes (PUs) in multiple aspects of modern lifestyle, the industrial scale manufacturing of PUs uses toxic chemicals like isocyanates, phosgene till today. In addition, the non-biodegradability and non-biocompatibility of PUs and their debris are serious cause of concerns for the environment. To deal with these challenges, in the current work, a new approach is reported in which bio-derived non-isocyanate polyurethanes were synthesized by exploiting viable amino acid-based diamines and biscyclocarbonates from sebacoyl chloride and diglycerol derivatives in a readily doable process. The newly designed polyhydroxyurethanes (PHUs) exhibited remarkable biodegradability and biocompatibility (cell viability) in comparison with commercial diamine based PHUs. A series of PHUs were synthesized in bulk and solvent free green synthetic route by polycondensing library of amino acids (such as glycine, alanine, valine, and isoleucine etc.) based diamines consisting of varying alkyl chain lengths and biscyclocarbonates like sebacic biscyclocarbonate and diglycerol biscyclocarbonate etc. All the synthesized PHUs were thoroughly characterised by IR, NMR and HRMS spectroscopic techniques. The impact of chain length and molecular structure of the synthesized PHUs were also evaluated using DSC, TGA, SEC, water contact angle measurements and hydrolytic degradation studies. The molar masses of the PHUs obtained from the SEC analysis are in the range of ∼17,000–24,000 Da. The current study demonstrated that amino acids is one of the major degradation products and are biocompatible in in-vitro conditions. The PHUs and their degradable products showed excellent cell viability when studied in HEK293T cells that were carried out using microgram to milligram concentration of PHUs. The outcome of this work in comparison to conventional PHUs and polyurethanes clearly demonstrated good biocompatibility and hence drawing attention to potential applications in bio-adhesives, bio-implants, drug delivery, and green coatings etc. in the near future.

Cationic Imidazolium-Urethane-Based Poly(Ionic Liquids) Membranes for Enhanced CO2/CH4 Separation: Synthesis, Characterization, and Performance Evaluation.

The escalating emissions of CO2 into the atmosphere require the urgent development of technologies aimed at mitigating environmental impacts. Among these, aqueous amine solutions and polymeric membranes, such as cellulose acetate and polyimide are commercial technologies requiring improvement or substitution to enhance the economic and energetic efficiency of CO2 separation processes. Ionic liquids and poly(ionic liquids) (PILs) are candidates to replace conventional CO2 separation technologies. PILs are a class of materials capable of combining the favorable gas affinity exhibited by ionic liquids (ILs) with the processability inherent in polymeric materials. In this context, the synthesis of the IL GLYMIM[Cl] was performed, followed by ion exchange processes to achieve GLYMIM variants with diverse counter anions (NTf2-, PF6-, and BF4). Subsequently, PIL membranes were fabricated from these tailored ILs and subjected to characterization, employing techniques such as SEC, FTIR, DSC, TGA, DMA, FEG-SEM, and CO2 sorption analysis using the pressure decay method. Furthermore, permeability and ideal selectivity assessments of CO2/CH4 mixture were performed to derive the diffusion and solubility coefficients for both CO2 and CH4. PIL membranes exhibited adequate thermal and mechanical properties. The PIL-BF4 demonstrated CO2 sorption capacities of 33.5 mg CO2/g at 1 bar and 104.8 mg CO2/g at 10 bar. Furthermore, the PIL-BF4 membrane exhibited permeability and ideal (CO2/CH4) selectivity values of 41 barrer and 44, respectively, surpassing those of a commercial cellulose acetate membrane as reported in the existing literature. This study underscores the potential of PIL-based membranes as promising candidates for enhanced CO2 capture technologies.

Polystyrene containing 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate with Low Molecular Weight Used As Macroadditive Photostabilizer

Photostabilizer additives are employed to shield polymer materials from ultraviolet (UV) degradation. One category of such additives includes ultraviolet light absorbers (UVA), which absorb radiation and dissipate it within the polymer network as heat. These additives are typically incorporated into the polymer during processing, but they can pose challenges such as low miscibility and migration of the additive to the polymer's surface. A viable solution to these issues is the synthesis of polymers with additives chemically connected to the polymer chain. This work investigates the copolymerization of styrene with the additive 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate (BHEM), resulting in the formation of PS-BHEM. This copolymer was then utilized in commercial polymers (PS, HIPS, and ABS) to mitigate degradation, with a comparative analysis of its effectiveness against the commercial stabilizer Tinuvin P. The copolymerization process yields a 92 % product, and the presence of BHEM is confirmed through SEC analysis. Accelerated weather degradation tests indicate that the incorporation of PS-BHEM enhances the UV stabilization of commercial ABS without altering the mechanical properties of the polymers.

A Sacrificial Linker in Biodegradable Polyesters for Accelerated Photoinduced Degradation, Monitored by Continuous Atline SEC Analysis.

Polymeric materials that undergo photoinduced degradation have wide application in fields such as controlled release. Most methods for photoinduced degradation rely on the UV or near-UV region of the electromagnetic spectrum; however, use of the deeply penetrating and benign wavelengths of visible light offers a multitude of advantages. Here we report a lactone monomer for ring-opening copolymerizations to introduce a sacrificial linker into a polymer backbone which can be cleaved by reactive oxygen species which are produced by a photocatalyst under visible light irradiation. We find that copolymers of this material readily degrade under visible light. We followed polymer degradation using a continuous flow size exclusion chromatography system, the components of which are described herein.

Adaptable SEC-SAXS data collection for higher quality structure analysis in solution.

The two major challenges in synchrotron size-exclusion chromatography coupled in-line with small-angle x-ray scattering (SEC-SAXS) experiments are the overlapping peaks in the elution profile and the fouling of radiation-damaged materials on the walls of the sample cell. In recent years, many post-experimental analyses techniques have been developed and applied to extract scattering profiles from these problematic SEC-SAXS data. Here, we present three modes of data collection at the BioSAXS Beamline 4-2 of the Stanford Synchrotron Radiation Lightsource (SSRL BL4-2). The first mode, the High-Resolution mode, enables SEC-SAXS data collection with excellent sample separation and virtually no additional peak broadening from the UHPLC UV detector to the x-ray position by taking advantage of the low system dispersion of the UHPLC. The small bed volume of the analytical SEC column minimizes sample dilution in the column and facilitates data collection at higher sample concentrations with excellent sample economy equal to or even less than that of the conventional equilibrium SAXS method. Radiation damage problems during SEC-SAXS data collection are evaded by additional cleaning of the sample cell after buffer data collection and avoidance of unnecessary exposures through the use of the x-ray shutter control options, allowing sample data collection with a clean sample cell. Therefore, accurate background subtraction can be performed at a level equivalent to the conventional equilibrium SAXS method without requiring baseline correction, thereby leading to more reliable downstream structural analysis and quicker access to new science. The two other data collection modes, the High-Throughput mode and the Co-Flow mode, add agility to the planning and execution of experiments to efficiently achieve the user's scientific objectives at the SSRL BL4-2.

Highly Efficient Biosorption of Cationic Dyes via Biopolymeric Adsorbent-Material-Based Pectin Extract Polysaccharide and Carrageenan Grafted to Cellulosic Nonwoven Textile.

Water scarcity and contamination have emerged as critical global challenges, requiring the development of effective and sustainable solutions for the treatment of contaminated water. Recently, functionalized polymer biomaterials have garnered significant interest because of their potential for a wide range of water treatment applications. Accordingly, this paper highlights the design of a new adsorbent material based on a cellulosic nonwoven textile grafted with two extracted biopolymers. The layer-by-layer grafting technique was used for the polyelectrolyte multi-layer (PEM) biosorbent production. Firstly, we extracted a Suaeda fruticosa polysaccharide (SFP) and confirmed its pectin-like polysaccharide structure via SEC, NMR spectroscopy, and chemical composition analyses. Afterward, the grafting was designed via an alternating multi-deposition of layers of SFP polymer and carrageenan crosslinked with 1,2,3,4-butanetetracarboxylic acid (BTCA). FT-IR and SEM were used to characterize the chemical and morphological characteristics of the designed material. Chemical grafting via polyesterification reactions of the PEM biosorbent was confirmed through FT-IR analysis. SEM revealed the total filling of material microspaces with layers of grafted biopolymers and a rougher surface morphology. The assessment of the swelling behavior revealed a significant increase in the hydrophilicity of the produced adsorbent system, a required property for efficient sorption potential. The evaluation of the adsorption capabilities using the methylene blue (MB) as cationic dye was conducted in various experimental settings, changing factors such as the pH, time, temperature, and initial concentration of dye. For the untreated and grafted materials, the greatest adsorbed amounts of MB were 130.6 mg/g and 802.6 mg/g, respectively (pH = 4, T = 22 C, duration = 120 min, and dye concentration = 600 mg/L). The high adsorption performance, compared to other reported materials, was due to the presence of a large number of hydroxyl, sulfonate, and carboxylic functional groups in the biosorbent polymeric system. The adsorption process fitted well with the pseudo-first-order kinetic model and Langmuir/Temkin adsorption isotherms. This newly developed multi-layered biosorbent shows promise as an excellent adsorption resultant and cheap-cost/easy preparation alternative for treating industrial wastewater.

Comparative analysis of hemostasis indices of sheep and lambs obtained taking into account body temperature

This paper shows the results of the study of the effect of temperature on the rate of coagulation processes in the blood plasma of small ruminants. The aim of the work was to compare the results of the study of blood coagulation indicators of sheep and lambs of Romanov and Edilbaev breed, obtained using medical and veterinary coagulometer, taking into account the age of the animal and its body temperature. The study was conducted in the Vologda region. The following parameters of coagulogram were analyzed: thrombin time, prothrombin time, activated partial thromboplastin time, amount and activity of fibrinogen. It was found that at physiologic temperature on veterinary coagulometer in plasma of sheep and lambs there is an increase of prothrombin time by 8,54 s and 15,24 s respectively, at that correlation-regression and one-factor dispersion analysis shows a positive moderate relationship between prothrombin time and plasma incubation temperature (r=0,3). In the plasma of lambs at the study with the setting of physiological temperature on the veterinary coagulometer there is an increase in the level of fibrinogen and its activity by 0.35 g and 4.53 sec, respectively, Correlation-regression and one-factor dispersion analysis showed a reliable high positive relationship between fibrinogen level and plasma incubation temperature (r=0,9) and a reliable high negative relationship between fibrinogen activity and plasma incubation temperature (r= -0,9). In this regard, a veterinary coagulometer with the possibility of setting the necessary temperature for adequate assessment of hemostasiological processes in sheep of different age groups can be recommended.

Synthesis and study of properties of new oligoesters based on soybean oil as potential poly(vinyl chloride) plasticizers

AbstractNew compounds as potential poly(vinyl chloride) plasticizers based on soybean oil and oligoesters of adipic acid and different glycols by one‐pot transesterification are synthesized. In the first step of the plasticizer synthesis oligoesters of adipic acid and diethylene glycol, triethylene glycol, or dipropylene glycol are synthesized, and then in situ in the second step, a defined amount of soybean oil is introduced. By degradation of soybean oil with oligoesters, and transesterification reaction, different compounds are obtained. Their physicochemical properties are determined by NMR, SEC, DSC, TGA, and volatility analyses. The properties of synthesized plasticizers are compared with commercial products: monomeric (DEHP) and aliphatic oligoster of adipic acid and 1,3‐butanediol (H‐1).

Influence of Rheological and Morphological Characteristics of Polyhydroxybutyrate on Its Meltblown Process Behavior.

Polyhydroxybutyrate (PHB) is a promising biopolymer. However, processing PHB in pure form in thermoplastic processes is limited due to its rapid degradation, very low initial crystallization rate, strong post-crystallization, and its low final stretchability. In this article, we screened commercial PHBs for morphological characteristics, rheological properties, and "performance" in the meltblown process in order to reveal process-relevant properties and overcome the shortcoming of PHB in thermoplastic processes for fiber formation. An evaluation of degradation (extruded (meltblown) material vs. granules) was performed via rheological and SEC analysis. The study revealed large differences in the minimum melt temperature (175 up to 200 °C) and the grade-dependent limitation of accessible throughput on a 500 mm plant. The average fiber diameter could be lowered from around 10 μm to 2.4 μm in median, which are the finest reported values in the literature so far. It was found that the determination of the necessary process temperature can be predicted well from the complex shear viscosity. Different to expectations, it became apparent that a broader initial molar mass distribution (>8) is suitable to overcome the state-of-the art limitations of PHAs in order to stabilize fiber formation, increase the productivity, and obtain better resistance towards thermal degradation in process. Accordingly, longer polymer chain fractions could be more affected by degradation than medium and short polymer chains in the distribution. Further, a low initial narrow distributed molar mass resulted in too brittle fabrics.

Precision Graphene Nanoribbon Heterojunctions by Chain-Growth Polymerization.

Graphene nanoribbons (GNRs) are considered promising candidates for next-generation nanoelectronics. In particular, GNR heterojunctions have received considerable attention due to their exotic topological electronic phases at the heterointerface. However, strategies for their precision synthesis remain at a nascent stage. Here, we report a novel chain-growth polymerization strategy that allows for constructing GNR heterojunction with N=9 armchair and chevron GNRs segments (9-AGNR/cGNR). The synthesis involves a controlled Suzuki-Miyaura catalyst-transfer polymerization (SCTP) between 2-(6'-bromo-4,4''-ditetradecyl-[1,1':2',1''-terphenyl]-3'-yl) boronic ester (M1) and 2-(7-bromo-9,12-diphenyl-10,11-bis(4-tetradecylphenyl)-triphenylene-2-yl) boronic ester (M2), followed by the Scholl reaction of the obtained block copolymer (poly-M1/M2) with controlled Mn (18k) and narrow Đ (1.45). NMR and SEC analysis of poly-M1/M2 confirm the successful block copolymerization. The solution-mediated cyclodehydrogenation of poly-M1/M2 toward 9-AGNR/cGNR is unambiguously validated by FT-IR, Raman, and UV-vis spectroscopies. Moreover, we also demonstrate the on-surface formation of pristine 9-AGNR/cGNR from the unsubstituted copolymer precursor, which is unambiguously characterized by scanning tunneling microscopy (STM).

Präzise Graphen‐Nanostreifen Heteroübergänge durch Kettenwachstumspolymerisation

AbstractGraphene‐Nanostreifen (GNS, engl. GNR) werden als vielversprechende Kandidaten für Nanoelektroniken der nächsten Generation gehandelt. Besonders Heteroübergänge in diesen Materialien erhalten durch ihre exotischen topologischen elektronischen Phasen am Heteroübergang in letzter Zeit viel Aufmerksamkeit. Allerdings sind Synthesestrategien für die atompräzise Synthese noch am Beginn ihrer Entwicklung. Hier berichten wir von einer neuartigen Strategie zur Kettenwachstumspolymerisation für die Konstruktion von Heteroübergängen zwischen N=9 Sessel‐GNR (engl. armchair, 9‐AGNR) und chevron GNRs (cGNR). Die Synthese beinhaltet eine kontrollierte Suzuki–Miyaura Katalysatortransferpolymerisation (engl. SCTP) zwischen 2‐(6′‐bromo‐4,4′′‐ditetradecyl‐[1,1′:2′,1′′‐terphenyl]‐3′‐yl)boronsäureester (M1) und 2‐(7‐bromo‐9,12‐diphenyl‐10,11‐bis(4‐tetradecylphenyl)‐triphenylen‐2‐yl)boronsäureester (M2) um das Blockcopolymer poly‐M1/M2 mit einem kontrollierten Mn (18 kDa) und einem schmalen Polydispersitätsindex Đ (1.45) zu erhalten. Darauf folgt eine Schollreaktion des Blockcopolymers zur Heterostruktur 9‐AGNR/cGNR. NMR und SEC von poly‐M1/M2 bestätigen die erfolgreiche Blockcopolymerisation. Die lösungsvermittelte Zyklodehydrierung von poly‐M1/M2 zu 9‐AGNR/cGNR wurde eindeutig über FT‐IR, Raman und UV/Vis Spektroskopie nachgewiesen. Weiter konnten wir die Ausbildung von 9‐AGNR/cGNR durch Oberflächenchemie des unsubstituierten Blockcopolymers mit Hilfe von Rastertunnelmikroskopie (RTM) direkt visualisieren.

Characterisation of geranylgeranyl diphosphate synthase from the sandfly Lutzomyia longipalpis

Leishmaniasis is a debilitating and often fatal neglected tropical disease. Males from sub-populations of the Leishmania-harbouring sandfly, Lutzomyia longipalpis, produce the diterpene sex and aggregation pheromone, sobralene, for which geranylgeranyl diphosphate (GGPP) is the likely isoprenoid precursor. We have identified a GGPP synthase (lzGGPPS) from L. longipalpis, which was recombinantly expressed in bacteria and purified for functional and kinetic analysis. In vitro enzymatic assays using LC-MS showed that lzGGPPS is an active enzyme, capable of converting substrates dimethylallyl diphosphate (DMAPP), (E)-geranyl diphosphate (GPP), (E,E)-farnesyl diphosphate (FPP) with co-substrate isopentenyl diphosphate (IPP) into (E,E,E)-GGPP, while (Z,E)-FPP was also accepted with low efficacy. Comparison of metal cofactors for lzGGPPS highlighted Mg2+ as most efficient, giving increased GGPP output when compared against other divalent metal ions tested. In line with previously characterised GGPPS enzymes, GGPP acted as an inhibitor of lzGGPPS activity. The molecular weight in solution of lzGGPPS was determined to be ∼221 kDa by analytical SEC, suggesting a hexameric assembly, as seen in the human enzyme, and representing the first assessment of GGPPS quaternary structure in insects.

The Effect of Sample Preparation Techniques on Lignin Fourier Transform Infrared Spectroscopy.

The characterization and quantification of functional groups in technical lignins are among the chief obstacles of the utilization of this highly abundant biopolymer. Although several techniques were developed for this purpose, there is still a need for quick, cost-efficient, and reliable quantification methods for lignin. In this paper, three sampling techniques for fourier transform infrared (FTIR) spectroscopy were assessed both qualitatively and quantitatively, delineating how these affected the resultant spectra. The attenuated total reflectance (ATR) of neat powders and DMSO-d6 solutions, as well as transmission FTIR using the KBr pelleting method (0.5 wt%), were investigated and compared for eight lignin samples. The ATR of neat lignins provided a quick and easy method, but the signal-to-noise ratios in the afforded spectra were limited. The ATR of the DMSO-d6 solutions was highly concentration dependent, but at a 30 wt%, acceptable signal-to-noise ratios were obtained, allowing for the lignins to be studied in the dissolved state. The KBr pelleting method gave a significant improvement in the smoothness and resolution of the resultant spectra compared to the ATR techniques. Subsequently, the content of phenolic OH groups was calculated from each FTIR mode, and the best correlation was seen between the transmission mode using KBr pellets and the ATR of the neat samples (R2 = 0.9995). Using the titration measurements, the total OH and the phenolic OH group content of the lignin samples were determined as well. These results were then compared to the FTIR results, which revealed an under-estimation of the phenolic OH groups from the non-aqueous potentiometric titration, which was likely due to the differences in the pKa between the lignin and the calibration standard 4-hydroxybenzoic acid. Further, a clear correlation was found between the lower Mn and the increased phenolic OH group content via SEC analyses. The work outlined in this paper give complementary views on the characterization and quantification of technical lignin samples via FTIR.

Structural characterisation of hemagglutinin from seven Influenza A H1N1 strains reveal diversity in the C05 antibody recognition site

Influenza virus (IV) causes several outbreaks of the flu each year resulting in an economic burden to the healthcare system in the billions of dollars. Several influenza pandemics have occurred during the last century and estimated to have caused 100 million deaths. There are four genera of IV, A (IVA), B (IVB), C (IVC), and D (IVD), with IVA being the most virulent to the human population. Hemagglutinin (HA) is an IVA surface protein that allows the virus to attach to host cell receptors and enter the cell. Here we have characterised the high-resolution structures of seven IVA HAs, with one in complex with the anti-influenza head-binding antibody C05. Our analysis revealed conserved receptor binding residues in all structures, as seen in previously characterised IV HAs. Amino acid conservation is more prevalent on the stalk than the receptor binding domain (RBD; also called the head domain), allowing the virus to escape from antibodies targeting the RBD. The equivalent site of C05 antibody binding to A/Denver/57 HA appears hypervariable in the other H1N1 IV HAs. Modifications within this region appear to disrupt binding of the C05 antibody, as these HAs no longer bind the C05 antibody by analytical SEC. Our study brings new insights into the structural and functional recognition of IV HA proteins and can contribute to further development of anti-influenza vaccines.

Structural Characterization of Polysaccharides from Coriandrum sativum Seeds: Hepatoprotective Effect against Cadmium Toxicity In Vivo.

Coriandrum sativum is one of the most widespread curative plants in the world, being vastly cultivated in arid and semi-arid regions as one of the oldest spice plants. The present study explored the extraction of polysaccharides from Coriandrum sativum seeds and the evaluation of their antioxidant potential and hepatoprotective effects in vivo. The polysaccharide from coriander seeds was extracted, and the structural characterization was performed by FT-IR, UV-vis, DSC, NMR (1D and 2D), GC-MS, and SEC analysis. The polysaccharide extracted from Coriandrum sativum (CPS) seeds was characterized to evaluate its antioxidant and hepatoprotective capacities in rats. Results showed that CPS was composed of arabinose, rhamnose, xylose, mannose, fructose, galactose, and glucose in molar percentages of 6.2%, 3.6%, 8.8%, 17.7%, 5.2%, 32.9%, and 25.6%, respectively. Further, CPS significantly hindered cadmium-induced oxidation damage and exercised a protective effect against Cd hepatocytotoxicity, with a considerable reduction in MDA production and interesting CAT and SOD enzyme levels. Results suggest that CPS might be employed as a natural antioxidant source.

The purely thermodynamic anti-prionic mode of action for the treatment of neurodegenerative diseases - realized by target protein specific all-D-peptides.

Neurodegenerative protein-misfolding diseases, like Alzheimer's (AD) and Parkinson's disease (PD), are driven by prion-like self-replicating and propagating protein assemblies of Aβ, α-synuclein, and many more. Therefore, we have developed the so-called anti-prionic mode of action (MoA). It is realized by all-D-enantiomeric peptide ligands that bind the monomeric protein of interest with high affinity, thereby stabilizing the physiological intrinsically disordered monomer structure. We call this purely thermodynamic driven mode of action “anti-prionic”, because it is eliminating already existing prion-like aggregates by disassembling them into non-toxic and functional monomers. I will summarize the current, and yet unpublished, progress in realizing the anti-prionic MoA for the target proteins α-synuclein and Aβ. Briefly, the most promising all-D-enantiomeric ligand for α-synuclein, SVD-1a, disassembles preformed α-synuclein fibrils (PFF) as shown by AFM, DLS and SEC analysis. SPR and NMR demonstrate picomolar affinity of SVD-1a to α-synuclein monomers, while keeping them in their physiological intrinsically disordered conformation. The all-D-enantiomeric ligand for Aβ, RD2, disassembles Aβ oligomers obtained from brain tissue of former AD patients. A clinical phase Ib, double-bind, placebo-controlled study with 20 ATN positive patients treated once daily orally with RD2 or placebo for 4 weeks with an additional 4 weeks follow up period demonstrates good safety and tolerability, and yields interesting results on efficacy. This is valuable information for the scheduled phase II study. I will also acknowledge the many contributors of both developments that are too many to be included here in the abstract. Conclusion: The unique anti-prionic mode of action for the treatment of AD, PD and other protein misfolding diseases is promising.

Increased ionic strength triggers multiple conformations in both apo and holo forms of bacterial ferric binding protein.

This study combines molecular dynamics (MD) simulations with solution X-ray scattering measurements to investigate the range of conformations that can be achieved by a pH/ionic strength (IS) sensitive protein and to quantify its distinct populations. To explore how the conformational multiplicity of proteins might be modified in the environmental niches of biological media, we focus on the periplasmic protein FbpA from H. influenzae which is a part of the mechanism developed by bacteria to capture iron from higher organisms. We examine iron-binding/release mechanisms of FbpA in varying conditions simulating its unique biological environment. The collected SAXS data complemented by SEC analyses and binding assays point to multiple conformations at physiological IS while they are well-explained by single x-ray structures in a 15 mM buffer. Moreover, by fitting the SAXS data with unique conformations sampled by a series of MD simulations carried out under conditions mimicking the buffers, we quantify with high accuracy the populations of the occupied substates. Furthermore, we find the D52A mutant that we predicted by coarse-grained computational approaches to allosterically control the iron binding site in FbpA responds to the environmental changes in our experiments with varied conformational selection scenarios. We show an application of the environment dependence of the conformers by designing a genetically encoded iron biosensor as a chimera of FbpA and green fluorescent protein using the D52 region as the insertion point. This work exemplifies how unifying a range of experimental and computational techniques provides platforms for achieving the next generation of applications that put protein dynamics rather than the static structure at the centerstage. Support by Turkish Atomic Energy Authority, TUBITAK grant no 121Z329 and a scholarship to GL through 2214-A program. Measurements conducted at EMBL-Hamburg.