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.

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.

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).

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.

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.

Structural changes of flavylium salts. II. Polargographic and spectrometric investigation of 4'-Hydroxyflavylium perchlorate

1967 ◽  
Vol 20 (4) ◽  
pp. 745 ◽  
Author(s):  
KA Harper ◽  
BV Chandler
Keyword(s):  
Structural Changes ◽  
Polarographic Reduction ◽  
Spectrometric Investigation ◽  
High Ph ◽  
Low Concentration ◽  
Methanolic Solution ◽  
Electrode Reactions ◽  
Wide Ph Range ◽  
Ph Range

4?-Hydroxyflavylium perchlorate is examined polarographically and spectrometrically in aqueous methanolic solution over a wide pH range. In solutions below pH 3 the flavonoid moiety exists solely as the flavylium ion, which establishes an equilibrium with the pseudobase, the anhydrobase, and the 2-hydroxychalcone above this pH. The flavylium ion disappears from solution above pH 5, the anhydrobase remains at a constant low concentration, and the ratio of pseudobase to chalcone fluctuates as the pH is increased. Electrode reactions for the various reductions are the same as those previously described for 7,4?- dihydroxyflavylium perchlorate. Without influencing the polarographic reduction, the presence of mercury in the polarographic cell favours chalcone formation in neutral solutions and suppresses resonance in the chalcone ion at high pH, probably through formation of a mercuric chelate.

Reduction of antimony by nano-particulate magnetite and mackinawite

2008 ◽  
Vol 72 (1) ◽  
pp. 185-189 ◽  
Author(s):  
R. Kirsch ◽  
A. C. Scheinost ◽  
A. Rossberg ◽  
D. Banerjee ◽  
L. Charlet
Keyword(s):  
Oxidation State ◽  
Photoelectron Spectroscopy ◽  
Redox Processes ◽  
Environmental Behaviour ◽  
X Ray ◽  
Ph Values ◽  
Wide Ph Range ◽  
Ph Range ◽  
X Ray Absorption

AbstractThe speciation of antimony is strongly influenced by its oxidation state (V, III, 0, —III). Redox processes under anaerobic groundwater conditions may therefore greatly alter the environmental behaviour of Sb. Employing X-ray absorption and photoelectron spectroscopy, we show here that Sb(V) is reduced to Sb(III) by magnetite and mackinawite, two ubiquitous Fe(II)-containing minerals, while Sb(III) is not reduced further. At the surface of magnetite, Sb(III) forms a highly symmetrical sorption complex at the position otherwise occupied by tetrahedral Fe(III). The Sb(V) reduction increases with pH, and at pH values >6.5 Sb(V) is completely reduced to Sb(III) within 30 days. In contrast, at the mackinawite surface, Sb(V) is completely reduced across a wide pH range and within 1 h. The Sb(V) reduction proceeds solely by oxidation of surface Fe(II), while the oxidation state of sulphide is conserved. Independent of whether Sb(V) or Sb(III) was added, an amorphous or nano-particulate SbS3-like solid formed.

Synthesis of Amino Methylene Phosphonic Acid Resin-Supported Hydrated Cerium Oxide Hybrid Sorbent and its Application in Drinking Water

2011 ◽  
Vol 183-185 ◽  
pp. 616-620
Author(s):  
Jun Feng Zhu ◽  
Guang Hua Zhang ◽  
Zhuo Miao ◽  
Shan Shan Yang ◽  
Bo Zhou
Keyword(s):  
Cerium Oxide ◽  
Phosphonic Acid ◽  
Ph Value ◽  
Adsorption Property ◽  
Ph Values ◽  
Acid Resin ◽  
Hybrid Sorbent ◽  
Wide Ph Range ◽  
Ph Range ◽  
Increasing Temperature

The hydrated cerium oxide (CeH) was synthesized and it was loaded on amino methylene phosphonic acid resin (APAR) to form the hybrid adsorbent CeH-APAR. The structure and thermal properties of CeH-APAR were tested by FTIR and TGA. And then, it was investigated that pH values and temperatures affected the adsorption property of CeH and CeH-APAR for fluoride ion. The results showed that CeH-APAR hybrid sorbent formed by Ce4+ and APAR with coordination bond is relatively stable below 270°C. Its adsorption property is similar to that of CeH, i.e. it is less affected by pH value, so it can be used in a wide pH range. Besides, under a stable pH, adsorption capacity of CeH-APAR also increases along with increasing temperature. As a result, it is a temperature-controlled sorbent and belongs to chemical adsorption.

scholarly journals Unmasking of histone amino groups in chromatin at high pH

1976 ◽  
Vol 159 (1) ◽  
pp. 173-175 ◽  
Author(s):  
B L Malchy ◽  
H Kaplan
Keyword(s):  
Acetic Anhydride ◽  
Amino Groups ◽  
High Ph ◽  
Ph Values ◽  
Ph Range

The reactivity of the amino groups of histones in chromatin towards acetic anhydride was determined as a function of pH. In the pH range 7-10 the vast majority of amino groups in all five histones are buried. However, at higher pH values some of the histone amino groups become exposed, and the higher the lysine:arginine ratio for the histone the greater was the degree of unmasking observed. At pH 11.8 histone I appears to be completely dissociated, histones IIB1 and IIb2 have approx. 55% of the amino groups unmasked, and histones III and IV have approx. 25% of the amino groups unmasked.

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