Fine-fibrous cellulose II aerogels of high specific surface from pulp solutions in TBAF·H2O/DMSO

Holzforschung ◽  
2018 ◽  
Vol 73 (1) ◽  
pp. 65-81 ◽  
Author(s):  
Christian B. Schimper ◽  
Paul Pachschwoell ◽  
Martin Wendland ◽  
Ena Smid ◽  
Marie-Alexandra Neouze ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Solvent Mixture ◽  
Size Exclusion ◽  
Cellulose Ii ◽  
Cellulose Solvent ◽  
Low Viscosity ◽  
A Value ◽  
Micron Size ◽  
Exclusion Chromatography ◽  
Chemical Integrity

Abstract Lightweight cellulose II aerogels featuring densities of about 40–70 mg cm−3 were prepared from 1 to 3% solutions of different pulps in hot (60°C) tetra-n-butylammonium fluoride (TBAF)·H2O/dimethyl sulfoxide (DMSO) by (i) the coagulation of cellulose with EtOH to afford self-standing, transparent and homogeneous gels, (ii) gel ripening and washing, (iii) solvent exchange and (iv) supercritical carbon dioxide (scCO2) drying. Size exclusion chromatography (SEC) analyses confirmed that the chemical integrity of cellulose is largely preserved at short dissolution times. Dissolution of more than 2% of cellulose at a sufficiently low viscosity for solution, casting was achieved after the water content of TBAF was reduced to a value equaling that of the monohydrate. Intriguingly, the obtained aerogels featured higher specific surfaces (≤470 m2 g−1) than comparable materials prepared from other cellulose solvents. This is due to the particular morphology of TBAF aerogels, which is supposedly formed by spinodal decomposition of the cellulose/solvent mixture upon exposure to the cellulose antisolvent. As a result, largely homogeneous three-dimensional (3D) networks of agglomerated cellulose spheres were formed, which simultaneously acted as supporting scaffolds for interconnected micron-size voids. As cellulose spheres are composed of very small interwoven nanofibers, TBAF-derived aerogels contain a high portion of micropores and small amounts of mesopores, too.

scholarly journals Dimerization of Human Angiogenin and of Variants Involved in Neurodegenerative Diseases

2021 ◽  
Vol 22 (18) ◽  
pp. 10068
Author(s):  
Sabrina Fasoli ◽  
Ilaria Bettin ◽  
Riccardo Montioli ◽  
Andrea Fagagnini ◽  
Daniele Peterle ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Three Dimensional ◽  
Size Exclusion ◽  
Active Site Residues ◽  
Ribonucleolytic Activity ◽  
Pathogenic Variants ◽  
Neuronal Progenitors ◽  
Tumor Tissues ◽  
Exclusion Chromatography ◽  
The Central Nervous System

Human Angiogenin (hANG, or ANG, 14.1 kDa) promotes vessel formation and is also called RNase 5 because it is included in the pancreatic-type ribonuclease (pt-RNase) super-family. Although low, its ribonucleolytic activity is crucial for angiogenesis in tumor tissues but also in the physiological development of the Central Nervous System (CNS) neuronal progenitors. Nevertheless, some ANG variants are involved in both neurodegenerative Parkinson disease (PD) and Amyotrophic Lateral Sclerosis (ALS). Notably, some pt-RNases acquire new biological functions upon oligomerization. Considering neurodegenerative diseases correlation with massive protein aggregation, we analyzed the aggregation propensity of ANG and of three of its pathogenic variants, namely H13A, S28N, and R121C. We found no massive aggregation, but wt-ANG, as well as S28N and R121C variants, can form an enzymatically active dimer, which is called ANG-D. By contrast, the enzymatically inactive H13A-ANG does not dimerize. Corroborated by a specific cross-linking analysis and by the behavior of H13A-ANG that in turn lacks one of the two His active site residues necessary for pt-RNases to self-associate through the three-dimensional domain swapping (3D-DS), we demonstrate that ANG actually dimerizes through 3D-DS. Then, we deduce by size exclusion chromatography (SEC) and modeling that ANG-D forms through the swapping of ANG N-termini. In light of these novelties, we can expect future investigations to unveil other ANG determinants possibly related with the onset and/or development of neurodegenerative pathologies.

scholarly journals Myriapod haemocyanin: the first three-dimensional reconstruction of Scolopendra subspinipes and preliminary structural analysis of S. viridicornis

Open Biology ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 190258
Author(s):  
K. C. T. Riciluca ◽  
A. C. Borges ◽  
J. F. R. Mello ◽  
U. C. de Oliveira ◽  
D. C. Serdan ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Signal Peptide ◽  
Oxygen Transport ◽  
Three Dimensional ◽  
Size Exclusion ◽  
Tem Analysis ◽  
Arthropod Species ◽  
Dimensional Reconstruction ◽  
Exclusion Chromatography ◽  
Respiratory Proteins

Haemocyanins (Hcs) are copper-containing, respiratory proteins that occur in the haemolymph of many arthropod species. Here, we report the presence of Hcs in the chilopode Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The analysis of transcriptome of S. subspinipes subpinipes reveals the presence of two distinct subunits of Hc, where the signal peptide is present, and six of prophenoloxidase (PPO), where the signal peptide is absent, in the 75 kDa range. Size exclusion chromatography profiles indicate different quaternary organization for Hc of both species, which was corroborated by TEM analysis: S. viridicornis Hc is a 6 × 6-mer and S. subspinipes Hc is a 3 × 6-mer, which resembles the half-structure of the 6 × 6-mer but also includes the presence of phenoloxidases, since the 1 × 6-mer quaternary organization is commonly associated with hexamers of PPO. Studies with Chelicerata showed that PPO activity are exclusively associated with the Hcs. This study indicates that Scolopendra may have different proteins playing oxygen transport (Hc) and PO function, both following the hexameric oligomerization observed in Hcs.

Fractional Clearance of Albumin is Influenced by its Degradation during Renal Passage

1997 ◽  
Vol 93 (6) ◽  
pp. 557-564 ◽  
Author(s):  
Tanya M. Osicka ◽  
Sianna Panagiotopoulos ◽  
George Jerums ◽  
Wayne D. Comper
Keyword(s):  
Size Exclusion ◽  
Gel Chromatography ◽  
Small Peptides ◽  
Isolated Perfused Kidney ◽  
A Value ◽  
Radioactivity Analysis ◽  
Fractional Clearance ◽  
Exclusion Chromatography ◽  
Perfused Kidney

1. The fractional clearance of intact albumin as determined by fractionation of urine by gel chromatography gave a value of 3.9 ± 1.6 × 10−4 for the isolated perfused kidney and 2.1 ± 0.6 × 10−4in vivo using ALZET osmotic pumps. 2. Albumin fractional clearance as measured by detection of the tritium label on the albumin molecule by radioactivity analysis gave a value of 7.5 ± 3.9 × 10−3 for the isolated perfused kidney and 2.3 ± 0.9 × 10−3in vivo. 3. The major differences between assays that detect intact albumin compared with non-specific assays in the estimates of the fractional clearance of albumin can be explained by the degradation of approx. 90% of albumin to small peptides during its renal passage. This has been demonstrated by size exclusion chromatography of urine samples from experiments where (i) exogenous tritium-labelled albumin was used in isolated perfused kidneys, (ii) exogenous tritium-labelled albumin was administered intravenously and (iii) analysis was made with metabolically labelled endogenous albumin in vivo.

scholarly journals Organophosphorus acid anhydrolase fromAlteromonas macleodii: structural study and functional relationship to prolidases

2013 ◽  
Vol 69 (4) ◽  
pp. 346-354 ◽  
Author(s):  
Andrea Štěpánková ◽  
Jarmila Dušková ◽  
Tereza Skálová ◽  
Jindřich Hašek ◽  
Tomáš Koval' ◽  
...  
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Size Exclusion ◽  
Dimensional Structure ◽  
Cell Parameters ◽  
Bacterial Enzyme ◽  
Organophosphorus Acid Anhydrolase ◽  
Full Structure ◽  
Exclusion Chromatography ◽  
Pita Bread

The bacterial enzyme organophosphorus acid anhydrolase (OPAA) is able to catalyze the hydrolysis of both proline dipeptides (Xaa-Pro) and several types of organophosphate (OP) compounds. The full three-dimensional structure of the manganese-dependent OPAA enzyme is presented for the first time. This enzyme, which was originally isolated from the marine bacteriumAlteromonas macleodii, was prepared recombinantly inEscherichia coli. The crystal structure was determined at 1.8 Å resolution in space groupC2, with unit-cell parametersa= 133.8,b= 49.2,c= 97.3 Å, β = 125.0°. The enzyme forms dimers and their existence in solution was confirmed by dynamic light scattering and size-exclusion chromatography. The enzyme shares the pita-bread fold of its C-terminal domain with related prolidases. The binuclear manganese centre is located in the active site within the pita-bread domain. Moreover, an Ni2+ion from purification was localized according to anomalous signal. This study presents the full structure of this enzyme with complete surroundings of the active site and provides a critical analysis of its relationship to prolidases.

scholarly journals Structure of Human Cyclophilin A in Complex with the Novel Immunosuppressant Sanglifehrin A at 1.6 Å Resolution

2005 ◽  
Vol 280 (23) ◽  
pp. 21965-21971 ◽  
Author(s):  
Joerg Kallen ◽  
Richard Sedrani ◽  
Gerhard Zenke ◽  
Juergen Wagner
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Cyclophilin A ◽  
The Other ◽  
Size Exclusion ◽  
Dimensional Structure ◽  
The Novel ◽  
Immunosuppressive Activity ◽  
Exclusion Chromatography ◽  
Sanglifehrin A

Sanglifehrin A (SFA) is a novel immunosuppressant isolated from Streptomyces sp. that binds strongly to the human immunophilin cyclophilin A (CypA). SFA exerts its immunosuppressive activity through a mode of action different from that of all other known immunophilin-binding substances, namely cyclosporine A (CsA), FK506, and rapamycin. We have determined the crystal structure of human CypA in complex with SFA at 1.6 Å resolution. The high resolution of the structure revealed the absolute configuration at all 17 chiral centers of SFA as well as the details of the CypA/SFA interactions. In particular, it was shown that the 22-membered macrocycle of SFA is deeply embedded in the same binding site as CsA and forms six direct hydrogen bonds with CypA. The effector domain of SFA, on the other hand, has a chemical and three-dimensional structure very different from CsA, already strongly suggesting different immunosuppressive mechanisms. Furthermore, two CypA·SFA complexes form a dimer in the crystal as well as in solution as shown by light scattering and size exclusion chromatography experiments. This observation raises the possibility that the dimer of CypA·SFA complexes is the molecular species mediating the immunosuppressive effect.

Impact of extracted algogenic organic matter on coagulation performance

2015 ◽  
Vol 15 (3) ◽  
pp. 617-624 ◽  
Author(s):  
Linan Xing ◽  
Christopher W. K. Chow ◽  
Jiane Zuo ◽  
Dongsheng Wang ◽  
Rolando Fabris ◽  
...  
Keyword(s):  
Organic Matter ◽  
Algal Blooms ◽  
High Performance ◽  
Three Dimensional ◽  
Product Formation ◽  
Size Exclusion ◽  
Uv Absorbance ◽  
Fluorescence Excitation ◽  
Before And After ◽  
Exclusion Chromatography

Understanding coagulation behaviour and treatability of waters impacted by algogenic organic matter (AOM) is important for waters with frequent algal blooms. Physico­­–chemical characteristics of AOM spiked into a water sample, before and after coagulation, were investigated using high-performance size exclusion chromatography (HPSEC) with UV and fluorescence detection, three dimensional-fluorescence excitation emission matrix (3D-FEEM) measurement and resin fractionation in which three fractions were determined including very hydrophobic acid (VHA), slightly hydrophobic acid (SHA) and hydrophilic fractions. Release of AOM from algal cells with consequential increases in dissolved organic carbon and UV absorbance led to changes in 3D-FEEM spectra indicative of increased aromatic protein presence. Changes in disinfection by-product formation potential after the AOM spiking indicated possible interactions between natural organic matter and AOM. A study of the treatability of the AOM spiked water using two coagulants, alum and a polyaluminum composite coagulant, was conducted with the relative percentages of UV absorbance values of both the SHA and hydrophilic fractions higher in the post coagulated AOM spiked water than in the coagulated water, with corresponding reductions in the VHA proportion. It was found that the increased SHA and hydrophilic components in the AOM spiked natural water were recalcitrant to removal by both coagulants.

scholarly journals Changes of Meranti, Padauk, and Merbau Wood Lignin during the ThermoWood Process

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 993
Author(s):  
Danica Kačíková ◽  
Ivan Kubovský ◽  
Milan Gaff ◽  
František Kačík
Keyword(s):  
Wood Species ◽  
Value Added ◽  
Thermal Modification ◽  
Size Exclusion ◽  
Technological Properties ◽  
Molecular Weights ◽  
A Value ◽  
Exclusion Chromatography ◽  
Environmentally Friendly Process ◽  
Syringyl To Guaiacyl Ratio

Thermal modification is an environmentally friendly process in which technological properties of wood are modified using thermal energy without adding chemicals, the result of which is a value-added product. Wood samples of three tropical wood species (meranti, padauk, and merbau) were thermally treated according to the ThermoWood process at various temperatures (160, 180, 210 °C) and changes in isolated lignin were evaluated by nitrobenzene oxidation (NBO), Fourier-transform infrared spectroscopy (FTIR), and size exclusion chromatography (SEC). New data on the lignins of the investigated wood species were obtained, e.g., syringyl to guaiacyl ratio values (S/G) were 1.21, 1.70, and 3.09, and molecular weights were approx. 8600, 4300, and 8300 g·mol−1 for meranti, padauk, and merbau, respectively. Higher temperatures cause a decrease of methoxyls and an increase in C=O groups. Simultaneous degradation and condensation reactions in lignin occur during thermal treatment, the latter prevailing at higher temperatures.

Some quantitative applications of vascular corrosion casting

1992 ◽  
Vol 50 (1) ◽  
pp. 738-739
Author(s):  
Fred E. Hossler
Keyword(s):  
Blood Vessels ◽  
Nuclear Orientation ◽  
Three Dimensional ◽  
Surrounding Tissue ◽  
Confocal Laser ◽  
Corrosion Casting ◽  
Venous Valve ◽  
Casting Technique ◽  
Low Viscosity ◽  
Quantitative Measurements

Preparation of replicas of the complex arrangement of blood vessels in various organs and tissues has been accomplished by infusing low viscosity resins into the vasculature. Subsequent removal of the surrounding tissue by maceration leaves a model of the intricate three-dimensional anatomy of the blood vessels of the tissue not obtainable by any other procedure. When applied with care, the vascular corrosion casting technique can reveal fine details of the microvasculature including endothelial nuclear orientation and distribution (Fig. 1), locations of arteriolar sphincters (Fig. 2), venous valve anatomy (Fig. 3), and vessel size, density, and branching patterns. Because casts faithfully replicate tissue vasculature, they can be used for quantitative measurements of that vasculature. The purpose of this report is to summarize and highlight some quantitative applications of vascular corrosion casting. In each example, casts were prepared by infusing Mercox, a methyl-methacrylate resin, and macerating the tissue with 20% KOH. Casts were either mounted for conventional scanning electron microscopy, or sliced for viewing with a confocal laser microscope.

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