scholarly journals Chemoenzymatic synthesis of the pH responsive surfactant octyl β-D-glucopyranoside uronic acid

2019 ◽  
Vol 104 (3) ◽  
pp. 1055-1062 ◽  
Author(s):  
Ngoc T. N. Ngo ◽  
Carl Grey ◽  
Patrick Adlercreutz
Keyword(s):  
Substrate Concentration ◽  
Uronic Acid ◽  
Catalyst System ◽  
Low Ph ◽  
Chemoenzymatic Synthesis ◽  
Ph Responsive ◽  
Ph Values ◽  
Wide Ph Range ◽  
Carboxyl Derivative ◽  
Ph Range

AbstractMethodology was developed to expand the range of benign alkyl glycoside surfactants to include also anionic types. This was demonstrated possible through conversion of the glycoside to its carboxyl derivative. Specifically, octyl β-D-glucopyranoside (OG) was oxidised to the corresponding uronic acid (octyl β-D-glucopyranoside uronic acid, OG-COOH) using the catalyst system T. versicolor laccase/2,2,6,6-tetramethylpiperidinyloxy (TEMPO) and oxygen from air as oxidant. The effects of oxygen supply methodology, concentrations of laccase, TEMPO and OG as well as reaction temperature were evaluated. At 10 mM substrate concentration, the substrate was almost quantitatively converted into product, and even at a substrate concentration of 60 mM, 85% conversion was reached within 24 h. The surfactant properties of OG-COOH were markedly dependent on pH. Foaming was only observed at low pH, while no foam was formed at pH values above 5.0. Thus, OG-COOH can be an attractive low-foaming surfactant, for example for cleaning applications and emulsification, in a wide pH range (pH 1.5–10.0).

A Ratiometric pH Responsive Fluorescence Probe for Monitoring Wide pH Range

2021 ◽  
Vol 6 (34) ◽  
pp. 9223-9229
Author(s):  
Sunanda Sahana ◽  
Vivekanand Sharma ◽  
Parimal K. Bharadwaj
Keyword(s):  
Fluorescence Probe ◽  
Ph Responsive ◽  
Wide Ph Range ◽  
Ph Range

scholarly journals Organic/Inorganic Superabsorbent Hydrogels Based on Xylan and Montmorillonite

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shuang Zhang ◽  
Ying Guan ◽  
Gen-Que Fu ◽  
Bo-Yang Chen ◽  
Feng Peng ◽  
...  
Keyword(s):  
Compressive Modulus ◽  
Cross Linking ◽  
Swelling Properties ◽  
Ph Values ◽  
Swelling Capacity ◽  
Wide Ph Range ◽  
Grafting Copolymerization ◽  
Ph Range ◽  
Influence Of Ph ◽  
Superabsorbent Hydrogels

The unique organic/inorganic superabsorbent hydrogels based on xylan and inorganic clay montmorillonite (MMT) were prepared via grafting copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) withN,N-methylenebisacrylamide (MBA) as a cross-linking agent and potassium persulfate (KPS) as an initiator. The effect of variables on the swelling capacity of the hydrogels, such as the weight ratios of MMT/xylan, MBA/xylan, and AMPS/AA, was systematically optimized. The results indicated that the superabsorbent hydrogels comprised a porous cross-linking structure of MMT and xylan with side chains that carry carboxylate, carboxamide, and sulfate. The hydrogels exhibit the high compressive modulus (E), about 35–55 KPa, and the compression strength of the hydrogels increased with an increment of the MMT content. The effect of various cationic salt solutions (LiCl, CaCl2, and FeCl3) on the swelling has the following order: Li+> Ca2+> Fe3+. Furthermore, the influence of pH values on swelling behaviors showed that the superabsorbent composites retained around 1000 g g−1over a wide pH range of 6.0–10.0. The xylan-based hydrogels with the high mechanical and swelling properties are promising for the applications in the biomaterials area.

Über die Wechselwirkung des Vanadyl(IV)-Kations mit Nucleobasen / Interaction of the Vanadyl(IV) Cation with Nucleic Bases

1993 ◽  
Vol 48 (12) ◽  
pp. 1845-1847 ◽  
Author(s):  
P. A. M. Williams ◽  
S. B. Etcheverry ◽  
E. J. Baran
Keyword(s):  
The Other ◽  
Ph Values ◽  
Nucleic Bases ◽  
Wide Ph Range ◽  
Ph Range ◽  
Oxygen Donors

The interaction of VO2+ with the nucleic bases adenine, guanine, cytosine, thymine and uracil has been investigated spectrophotometrically in a wide pH-range and with metal to base ratios 1:1 and 1:10. Adenine, guanine and uracil interact with the cation at pH-values >5, but whereas adenine apparently coordinates through Natoms, the other two bases seem to be coordinated through oxygen donors.

Morphogenesis-Associated/Dissociated Production of Epothilone in Wild Sorangium Cellulosum Strains

2011 ◽  
Vol 343-344 ◽  
pp. 951-957
Author(s):  
Xin Li Liu ◽  
Lin Zhao ◽  
Wei Hu ◽  
Yue Zhong Li
Keyword(s):  
Fruiting Body ◽  
Fruiting Bodies ◽  
Sorangium Cellulosum ◽  
Strongly Coupled ◽  
High Ph ◽  
Ph Values ◽  
Wide Ph Range ◽  
Ph Range

To investigate the characters ofSorangiumstrains and the approaches for improving the production of epothilone, correlation of epothilone production and morphogenesis was studied in strains So0157-2, So0007-3andSo0003-3. On lean medium, So0157-2 could produce epothilones in a wide pH range (5.0-12.0), but formed fruiting bodies at high pH values (9.0-14.0). Formation of fruiting body did not affect the yield of epothilones in So0157-2. In So0007-3 and So0003-3, producing of epothilone was strongly coupled with the process of morphogenesis. It suggests that reduction of the association between morphogenesis and epothilone producing would prominently improve the epothilone production.

Rational design of porous binary Pt-based nanodendrites as efficient catalysts for direct glucose fuel cells over a wide pH range

2017 ◽  
Vol 7 (13) ◽  
pp. 2819-2827 ◽  
Author(s):  
Kamel Eid ◽  
Yahia H. Ahmad ◽  
Siham Y. AlQaradawi ◽  
Nageh K. Allam
Keyword(s):  
Catalytic Activity ◽  
Oxidation Reaction ◽  
Rational Design ◽  
Glucose Oxidation ◽  
Room Temperature ◽  
Ph Values ◽  
Wide Ph Range ◽  
One Step ◽  
Ph Range ◽  
Glucose Oxidation Reaction

Porous binary PtPd, AuPt, PtCu, and PtNi nanodendrites prepared by a facile one-step reduction under ultrasonic irradiation at room temperature, exhibited a substantial catalytic activity towards glucose oxidation reaction at different pH values relative to a commercial Pt/C catalyst.

Preparation and Structural Characterization of Methylmercury(II) Complexes of 5-Aza- and 6-Azauracil Derivatives

1987 ◽  
Vol 42 (12) ◽  
pp. 1556-1562 ◽  
Author(s):  
W. S. Sheldrick ◽  
S. Heeb
Keyword(s):  
Structural Analysis ◽  
Binding Sites ◽  
Ionic Complex ◽  
X Ray ◽  
H Nmr ◽  
Ph Values ◽  
Nmr Data ◽  
Wide Ph Range ◽  
Ph Range

Abstract1:1 Methylmercury(II) complexes of the anti-tumour agent 6-azauracil (6AUH2) and its deriva­tives 6-azathymine (6ATH2). 1-methyl-6-azauracil (6AMUH) and 1-methyl-6-azathymine (6AMTH) have been isolated from aqueous solutions of CH3HgOH and the respective base. N3-Coordination was established by X-ray structural analysis for both [(CH3Hg)6 AUH] (1) (pH 6-8) and [(CH3Hg)6 AMT] (5) (pH 4-12); in addition 1H NMR data are in accordance with an identical binding site in the complexes [(CH3Hg)6AMU] (3) and [(CH3Hg)6 ATH] (4). Using an excess of CH3HgOH. 2:1 complexes with N1, N3-coordination may be prepared for both 6 AUH: and 5 AUH2 in a wide pH range (4-12 and 6-12 respectively). At pH values of 3-4 a 3:1 complex [(CH3Hg)35 AU]NO3 (7), with N1, N3, N5-coordination may be isolated: the binding sites were confirmed by X-ray structural analysis. In no case could an ionic complex with N6- coordination be isolated for a 6-azapyrimidine derivative. The binding preferences of the bases are discussed in the light of MNDO calculations.

Conserved amphiphilic feature is essential for periplasmic chaperone HdeA to support acid resistance in enteric bacteria

2008 ◽  
Vol 412 (2) ◽  
pp. 389-397 ◽  
Author(s):  
Ye E. Wu ◽  
Weizhe Hong ◽  
Chong Liu ◽  
Lingqing Zhang ◽  
Zengyi Chang
Keyword(s):  
Pathogenic Bacteria ◽  
Acid Resistance ◽  
Enteric Bacteria ◽  
Structural Features ◽  
Low Ph ◽  
Hydrophobic Region ◽  
Ph Values ◽  
Ph Conditions ◽  
Stomach Ph ◽  
Ph Range

The extremely acidic environment of the mammalian stomach (pH 1–3) represents a stressful challenge for enteric pathogenic bacteria, including Escherichia coli, Shigella and Brucella. The hdeA (hns-dependent expression A) gene was found to be crucial for the survival of these enteric bacteria under extremely low pH conditions. We recently demonstrated that HdeA is able to exhibit chaperone-like activity exclusively within the stomach pH range by transforming from a well-folded conformation at higher pH values (above pH 3) into an unfolded conformation at extremely low pH values (below pH 3). This study was performed to characterize the action mechanisms and underlying specific structural features for HdeA to function in this unfolded conformation. In the present study, we demonstrate that the conserved ‘amphiphilic’ feature of HdeA, i.e. the exposure of the conserved hydrophobic region and highly charged terminal regions, is essential for exhibiting chaperone-like activity under extremely low pH conditions. Mutations that disrupt this amphiphilic feature markedly reduced the chaperone-like activity of HdeA. The results also strongly suggest that this acid-induced chaperone-like activity of HdeA is crucial for acid resistance of the enteric bacteria. Moreover, our new understanding of this amphiphilic structural feature of HdeA helps to better interpret how this unfolded (disordered) conformation could be functionally active.

Investigation of the Range of a Plastic pH Sensor Based on a Dibasic Ionophore

1992 ◽  
Vol 45 (2) ◽  
pp. 435 ◽  
Author(s):  
TJ Cardwell ◽  
RW Cattrall ◽  
LW Deady ◽  
KA Murphy
Keyword(s):  
Positive Charge ◽  
Ph Sensor ◽  
Low Ph ◽  
Membrane Electrode ◽  
Neutral Carrier ◽  
Ph Values ◽  
Response Range ◽  
Ph Scale ◽  
Ph Range ◽  
Sensitive Membrane

A study is reported of the use of a neutral carrier reagent containing two nitrogen atoms with very different basicities in a pH-sensitive membrane electrode with a view to obtaining a broad response range. This electrode responds well in the pH region of 6-12 but suffers anion interference in the region of pH 2-6. A study is included of the effect of adding various amounts of potassium tetrakis(4-chloropheny1)borate as an anion suppressing reagent to the membrane in order to reduce the anion interference at low pH values. The conclusion is drawn that an extension to the working pH range is not possible with this approach unless controlled amounts of anion suppressing reagent can be provided to approximately balance the positive charge of the carrier in each region of the pH scale.

scholarly journals Dodecyl sulphate/polyacrylamide-gel electrophoresis at low pH values and low temperatures

1979 ◽  
Vol 181 (3) ◽  
pp. 759-761 ◽  
Author(s):  
R Lichtner ◽  
H U Wolf
Keyword(s):  
Low Temperatures ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Catalyst System ◽  
Low Ph ◽  
Polyacrylamide Gel ◽  
Buffer System ◽  
Simple Method ◽  
Ph Values

A simple method is described for dodecyl sulphate/polyacrylamide-gel electrophoresis of pH- and temperature-labile biological intermediates. The method is based on a catalyst system that works at temperatures of 2–4 degrees C and pH values of 2–4 and an appropriate buffer system containing Li+ or Tris [CH2OH–C(CH2OH)2–NH3+] instead of Na+. This system does not lead to the precipitation of 1% dodecyl sulphate.

scholarly journals Differential Sensitivity of Phytophthora parasitica var. nicotianae and Thielaviopsis basicola to Monomeric Aluminum Species

2006 ◽  
Vol 96 (3) ◽  
pp. 212-220 ◽  
Author(s):  
E. J. Fichtner ◽  
D. L. Hesterberg ◽  
T. J. Smyth ◽  
H. D. Shew
Keyword(s):  
Plant Pathogens ◽  
Differential Sensitivity ◽  
Thielaviopsis Basicola ◽  
Phytophthora Parasitica ◽  
Ph Values ◽  
Wide Ph Range ◽  
Pathogen Suppression ◽  
Multiple Species ◽  
Ph Range ◽  
Treatment Design

Aluminum (Al) is toxic to many plant pathogens, including Thielaviopsis basicola and Phytophthora parasitica var. nicotianae. Because fungi-toxicity of Al has been described in soils over a wide pH range, multiple species of Al may be responsible for pathogen suppression. The goals of this work were to determine the sensitivity of T. basicola and P. para-sitica var. nicotianae to Al over a range of pH values, quantify the toxicity of monomeric Al species to production of sporangia of P. parasitica var. nicotianae and chlamydospores of T. basicola, and detect the accumulation of Al in pathogen structures. A complete factorial treatment design was used with Al levels ranging from 0 to 100 μM and pH levels ranging from 4 to 6 in a minimal salts medium. The chemistry of test solutions was modeled using GEOCHEM-PC. Colonies were grown in 5% carrot broth, and after 1 or 2 days, the nutrient solution was removed, colonies were rinsed with water, and Al test solutions were added to each of four replicate plates. After 2 days, propagules were counted and colonies were stained with the Al-specific, fluorescent stain lumogallion. The oomycete P. parasitica var. nicotianae was sensitive to multiple monomeric Al species, whereas sensitivity of T. basicola to Al was pH-dependent, suggesting that only Al3+ is responsible for suppression of this fungal pathogen. Chlamydospore production by T. basicola was inhibited at pH values <5.0 and Al levels >20 μM, whereas sporangia production by P. parasitica was inhibited at Al levels as low as 2 μM across all pH values tested. The lumogallion stain was an effective technique for detection of Al in fungal tissues. Aluminum accumulated in sporangia and zoospores of P. parasitica var. nicotianae and in nonmelanized chlamy-dospores of T. basicola, but not in cell walls of either organism. The differential sensitivity of the two organisms may indicate that true fungi respond differently to Al than members of the oomycota, which are more closely related to plants.

Sign in / Sign up

Export Citation Format

Share Document