scholarly journals Genetic Improvement of Bacillus licheniformis Strains for Efficient Deproteinization of Shrimp Shells and Production of High-Molecular-Mass Chitin and Chitosan

2010 ◽  
Vol 76 (24) ◽  
pp. 8211-8221 ◽  
Author(s):  
Kerstin Hoffmann ◽  
Gabriele Daum ◽  
Marina Köster ◽  
Werner-Michael Kulicke ◽  
Heike Meyer-Rammes ◽  
...  
Keyword(s):  
Bacillus Licheniformis ◽  
Chitinase Activity ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Phenotypic Properties ◽  
Double Deletion ◽  
Shrimp Shells ◽  
Proteolytic Activities ◽  
Chitin And Chitosan ◽  
Long Chain

ABSTRACT By targeted deletion of the polyglutamate operon (pga) in Bacillus licheniformis F11, a derivative form, F11.1 (Δpga), was obtained that, along with lacking polyglutamate (PGA) formation, displayed enhanced proteolytic activities. The phenotypic properties were maintained in a strain in which the chiBA operon was additionally deleted: F11.4 (ΔchiBA Δpga). These genetically modified strains, carrying the Δpga deletion either alone (F11.1) or together with the ΔchiBA (F11.4) deletion, were used in fermentations (20-liter scale) aiming at the deproteinization of shrimp shells in order to obtain long-chain chitin. After chemical deacetylation, the resulting chitosan samples were analyzed by nuclear magnetic resonance spectroscopy, size exclusion chromatography, and viscometry and compared to a chitosan preparation that was produced in parallel by chemical methods by a commercial chitosan supplier (GSRmbH). Though faint lipid impurities were present in the fermented polysaccharides, the viscosity of the material produced with the double-deletion mutant F11.4 (Δpga ΔchiBA) was higher than that of the chemically produced and commercially available samples (Cognis GmbH). Thus, enhanced proteolytic activities and a lack of chitinase activity render the double mutant F11.4 a powerful tool for the production of long-chain chitosan.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

scholarly journals Effect of DMPA and Molecular Weight of Polyethylene Glycol on Water-Soluble Polyurethane

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Polyethylene Glycol ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Soft Segment ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

Molecular and biochemical characteristics of inulosucrase InuBK from Alkalihalobacillus krulwichiae JCM 11 691

2021 ◽  
Author(s):  
Ken-ji Yokoi ◽  
Sosyu Tsutsui ◽  
Gen-ya Arakawa ◽  
Masakazu Takaba ◽  
Koichi Fujii ◽  
...  
Keyword(s):  
High Performance ◽  
Culture Medium ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Gene Encoding ◽  
Reading Frame ◽  
Exclusion Chromatography ◽  
Chain Lengths

Abstract Information about the inulosucrase of non-lactic acid bacteria is scarce. We found a gene encoding inulosucrase (inuBK) in the genome of the gram-positive bacterium Alkalihalobacillus krulwichiae JCM 11691. The inuBK open reading frame encoded a protein comprising 456 amino acids. We expressed His-tagged InuBK in culture medium using a Brevibacillus system. The optimal pH and temperature of purified InuBK were 7.0–9.0 and 50 °C–55 °C, respectively. The findings of high-performance anion-exchange chromatography, nuclear magnetic resonance spectroscopy, and high-performance size-exclusion chromatography with multi-angle laser light scattering showed that the polysaccharide produced by InuBK was an inulin with a molecular weight of 3,806, a polydispersity index (PI) of 1.047, and fructosyl chain lengths with 3–27 degrees of polymerization. The size of InuBK was smaller than commercial inulins, and the PI of the inulin that it produced was lower.

scholarly journals Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(ε-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1252
Author(s):  
Rodolfo M. Moraes ◽  
Layde T. Carvalho ◽  
Gizelda M. Alves ◽  
Simone F. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Ring Opening ◽  
Chain Transfer ◽  
Fluorescence Probe ◽  
Size Exclusion ◽  
Proton Nuclear Magnetic Resonance ◽  
Solution Temperature ◽  
Copolymer Composition ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(ε-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X–PNVCL–OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of ε-caprolactone (ε-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), UV–vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV–vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition.

Influence of molecular structure on the rheological properties and foamability of long chain branched polypropylene by “one-pot” reactive extrusion

2020 ◽  
pp. 0021955X2094310
Author(s):  
Yan Li ◽  
Zhen Yao ◽  
Shaolong Qiu ◽  
Changchun Zeng ◽  
Kun Cao
Keyword(s):  
Coupling Reaction ◽  
Reactive Extrusion ◽  
Expansion Ratio ◽  
Size Exclusion ◽  
One Pot ◽  
Synthesis Conditions ◽  
Twin Screw ◽  
Exclusion Chromatography ◽  
In Series ◽  
Long Chain

In this work, reactive twin screw extrusion was conducted to synthesize long chain branched polypropylenes (LCB-PPs) in a “one-pot” process in which dicumyl peroxide (DCP) initiated maleic anhydride (MAH) grafting onto the linear PP, and the concomitant coupling reaction between ethylene diamine (EDA) and MAH grafted polypropylene (PP-g-MAH) proceeded in series. Fourier transfer infrared spectroscopy (FTIR) on the prepared materials confirmed the occurrence of both reactions. A series of LCB-PPs were prepared using different amounts of EDA, MAH and DCP to study their effects and determine the optimal synthesis conditions. The prepared materials were characterized by size exclusion chromatography (SEC) and rheological analysis to ascertain the polymer microstructure. The foamability of the LCB-PPs by supercritical carbon dioxide (scCO2) foaming and foam morphology were investigated. The LCB-PPs were found to have vastly improved foamability and cellular morphology. Under optimal conditions, a foam expansion ratio of over 20 was achieved.

Characterization of chitin and chitosan extracted from shrimp shells by two methods

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Carmiña Gartner ◽  
Carlos Alberto Peláez ◽  
Betty Lucy López
Keyword(s):  
Low Cost ◽  
Magic Angle Spinning ◽  
Chemical Extraction ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Shrimp Shells ◽  
Before And After ◽  
Chitin Extraction ◽  
Angle Spinning ◽  
Chitin And Chitosan

AbstractShrimp shells from Penaeus Vannamei species were hydrolyzed for chitin extraction by a chemical and a papain enzymatic method. Composition of shells was analyzed and their microstructure was characterized before and after hydrolysis by microscopy. Chitin fibers arrangement in the tissue was preserved after chemical extraction, but after papain hydrolysis the tissue presented structural disarrangement indicating that papain reacts indistinctly with peptidic and N-acetyl linkages. Although chemical purification is very effective, by-products are not recoverable. Conversely, papain hydrolysis yields partially purified chitosan but permits aminoacids isolation, which is important in food industry. This method has other advantages such as low cost and easy accessibility of papain. Chitin and chitosan were characterized by thermogravimetric analysis, infrared spectrophotometry and capillary electrophoresis. Degree of N-acetylation (DA) was determined by cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS 13CNMR) or potentiometry and crystallinity was measured by X ray diffraction.

scholarly journals A T cell receptor V alpha domain expressed in bacteria: does it dimerize in solution?

1996 ◽  
Vol 184 (4) ◽  
pp. 1251-1258 ◽  
Author(s):  
D Plaksin ◽  
S Chacko ◽  
P McPhie ◽  
A Bax ◽  
E A Padlan ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Cell Receptor ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Gel Chromatography ◽  
Mhc Class I Molecule

To evaluate the potential for dimerization through a particular T cell receptor (TCR) domain, we have cloned the cDNA encoding a TCR V alpha from a hybridoma with specificity for the human immunodeficiency virus (HIV) envelope glycoprotein 120-derived peptide P18-110 (RGPGRAFVTI) bound to the murine major histocompatibility complex (MHC) class I molecule, H-2Dd. This cDNA was then expressed in a bacterial vector, and protein, as inclusion bodies, was solubilized, refolded, and purified to homogeneity. Yield of the refolded material was from 10 to 50 mg per liter of bacterial culture, the protein was soluble at concentrations as high as 25 mg/ml, and it retained a high level of reactivity with an anti-V alpha 2 monoclonal antibody. This domain was monomeric both by size exclusion gel chromatography and by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Circular dichroism spectra indicated that the folded V alpha domain had secondary structure similar to that of single immunoglobulin or TCR domains, consisting largely of beta sheet. Conditions for crystallization were established, and at least two crystal geometries were observed: hexagonal bipyramids that failed to diffract beyond approximately 6 A, and orthorhombic crystals that diffracted to 2.5 A. The dimerization of the V alpha domain was investigated further by solution nuclear magnetic resonance spectroscopy, which indicated that dimeric and monomeric forms of the protein were about equally populated at a concentration of 1 mM. Thus, models of TCR-mediated T cell activation that invoke TCR dimerization must consider that some V alpha domains have little tendency to form homodimers or multimers.

Sign in / Sign up

Export Citation Format

Share Document