Photolysis of Aqueous Solutions of 9,10-Anthraquinone-2-sulfonate. Part I. Dependence of Product Yields on Reaction Conditions

1972 ◽  
Vol 50 (3) ◽  
pp. 381-387 ◽  
Author(s):  
A. D. Broadbent ◽  
R. P. Newton
Keyword(s):  
Aqueous Solutions ◽  
High Oxygen ◽  
Low Oxygen ◽  
Reaction Conditions ◽  
Fenton's Reagent ◽  
Product Yields ◽  
Preferential Formation ◽  
Naoh Solution ◽  
Derivatives Of ◽  
Oxygen Concentrations

The products of the photolysis of neutral aqueous solutions of 9,10-anthraquinone-2-sulfonate or of the action of Fenton's reagent on this quinone have been identified as 1- and 2-hydroxy- and dihydroxy-9,10-anthraquinone sulfonates. High quinone and low oxygen concentrations favor production of monohydroxy-anthraquinone sulfonates, while low quinone and high oxygen concentrations result in preferential formation of dihydroxylated derivatives of the quinone. Photolysis in aqueous NaOH solution gives essentially only 2-hydroxy-9,10-anthraquinone sulfonates.

Photolysis of Aqueous Solutions Of 9,10-Anthraquinone-2-Sulfonate. Part II. Dependence of Rates of Hydroxylation on Reaction Conditions

1975 ◽  
Vol 53 (6) ◽  
pp. 826-830 ◽  
Author(s):  
Arthur D. Broadbent ◽  
Hugh B. Matheson ◽  
Richard P. Newton
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Incident Light ◽  
Maximum Quantum Yield ◽  
Reaction Conditions ◽  
Naoh Solution ◽  
High Concentrations ◽  
Constant Maximum ◽  
Limiting Value

The rates of formation of hydroxy-9,10-anthraquinone-2-sulfonates, produced by irradiation of neutral and alkaline aqueous solutions of 9,10-anthraquinone-2-sulfonate (A) at 365 nm, have been measured for solutions with initial [A] ranging from 5 × 10−5 to 8 × 10−2 mol dm−3, saturated with either O2, air, or N2. The rate of monohydroxylation was independent of the saturating gas and, for neutral solutions absorbing all the incident light, increased with increasing initial [A] reaching a constant maximum quantum yield of 0.08 above 2 × 10−2 mol dm−3. In 0.1 mol dm−3 aqueous NaOH solution, the rate was about three times larger but had not attained a limiting value at the maximum [A] imposed by its solubility. Dihydroxy-9,10-anthraquinone sulfonates are proposed to arise from reaction of O2 with an intermediate, rather than by further hydroxylation of monohydroxy products. The rate of dihydroxylation decreased on increasing [A] above 5 × 10−4 mol dm−3, becoming essentially zero at high concentrations.

scholarly journals Staphylococcus epidermidismetabolic adaptation and biofilm formation in response to varying oxygen

2019 ◽  
Author(s):  
Ulrik H. Pedroza-Dávila ◽  
Cristina Uribe-Alvarez ◽  
Lilia Morales-García ◽  
Emilio Espinoza-Simón ◽  
Adriana Muhlia-Almazán ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Respiratory Activity ◽  
Health Hazard ◽  
High Oxygen ◽  
Host Cells ◽  
Metabolic Inhibitors ◽  
Low Oxygen ◽  
High Hydrogen ◽  
Oxygen Concentrations

ABSTRACTStaphylococcus epidermidisis a Gram-positive saprophytic bacterium found in the microaerobic/anaerobic layers of the skin. It becomes a health hazard when introduced across the skin by punctures or wounds.S. epidermidisforms biofilms in low O2environments. As oxygen concentrations ([O2]) decreased, the metabolism ofS. epidermidiswas modified ranging from fully aerobic to anaerobic. Respiratory activity increased at high [O2], while anaerobically grown cells exhibited the highest rate of fermentation. High aerobic metabolism coincided with high hydrogen peroxide-mediated damage. Remarkably, the rate of growth decreased at low [O2] even though the concentration of ATP was high. Under these conditions bacteria associated into biofilms. Then, in the presence of metabolic inhibitors, biofilm formation decreased. It is suggested that when [O2] is lowS. epidermidisaccumulates ATP in order to synthesize the proteins and polysaccharides needed to attach to surfaces and form biofilms.ImportanceBacteria and humans coexist, establishing all kinds of relationships that may change from saprophytic to infectious as environmental conditions vary. S. epidermidis is saprophytic when living in the skin. Inside the organism it evokes a pathologic reaction and is thus rejected by the organism. Additionally it is forced to adapt to high oxygen concentrations, becoming vulnerable to reactive oxygen species, which may come from leukocyte attack. Avoiding both, high oxygen and leukocytes is a must for bacteria. Escaping from oxygen involves a clever response: whenever it finds a low oxygen environment it attaches to surfaces, associating into biofilms. Biofilms protectS. epidermidisagainst host cells. Understanding these responses is a must in order to develop treatments and prevent infection success.

Developmental competence of porcine oocytes after in vitro maturation and in vitro culture under different oxygen concentrations

Zygote ◽  
2011 ◽  
Vol 20 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Jung-Taek Kang ◽  
Mohammad Atikuzzaman ◽  
Dae-Kee Kwon ◽  
Sol-Ji Park ◽  
Su-Jin Kim ◽  
...  
Keyword(s):  
Embryo Development ◽  
Cumulus Cells ◽  
Cyclin B1 ◽  
High Oxygen ◽  
Developmental Competence ◽  
Low Oxygen ◽  
Multiple Genes ◽  
Significant Difference ◽  
Oxygen Concentrations

SummaryIn this study, we investigated the effect of two oxygen concentrations (5 and 20%) during in vitro maturation (IVM) and during in vitro culture (IVC) on porcine embryo development and analysed differences in gene expression between cumulus–oocyte complexes matured under 5 or 20% oxygen and the resulting blastocysts cultured under 5% or 20% oxygen following parthenogenetic activation. There was no significant difference in oocyte maturation rate. However, the numbers of resulting blastocysts were significantly increased in the 5% IVC group compared with the 20% IVC group. Moreover, the M20C5 treatment group (23.01%) supported greater blastocyst development compared with the M5C5 (14.32%), M5C20 (10.30%), and M20C20 (17.88%) groups. However, total cell numbers were not significantly different among groups. According to mRNA abundance data of multiple genes, each treatment altered the expression of genes in different patterns. GLUT1, G6PD and LDHA were up-regulated in cumulus cells that had been matured in low oxygen, suggesting a higher glucose uptake and an increase in anaerobic glycolysis, whereas cyclin B1 (CCNB) and MnSOD (Mn-superoxide dismutase) were upregulated in cumulus cells that had been matured in high oxygen, which suggests a higher activity of mitosis-promoting factor and antioxidant response. In spite of these differential effects on cumulus cells, oocytes could mature normally regardless of different oxygen concentrations. Therefore, it can be concluded that high oxygen concentration during in vitro maturation and low oxygen during in vitro culture may alter the expression of multiple genes related to oocyte competence and significantly improves embryo development (p < 0.05) but not blastocyst quality.

Effects of salts on the kinetics of oxidation of alkenes by thallic salts in aqueous solutions

1981 ◽  
Vol 46 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Milan Strašák ◽  
Jaroslav Majer
Keyword(s):  
Aqueous Solutions ◽  
Phase Transfer ◽  
Heterogeneous Reaction ◽  
Qualitative Model ◽  
Kinetic Effect ◽  
Tetraalkylammonium Salts ◽  
Reaction Conditions ◽  
Kinetics Of Oxidation ◽  
Kinetics Of ◽  
Heterogeneous Reaction Conditions

The kinetics of oxidation of alkenes by thallic sulphate in aqueous solutions, involving the two reaction steps-the hydroxythallation and the dethallation - was studied, and the effect of salts on the kinetics was examined; this made it possible to specify more precisely the reaction mechanism and to suggest a qualitative model of the reaction coordinate. It was found that in homogeneous as well as in heterogeneous reaction conditions, the reaction can be accelerated appreciably by adding tetraalkylammonium salts. These salts not only operate as catalysts of the phase transfer, but also exert a significant kinetic effect, which can be explained with a simplification in terms of a stabilization of the transition state of the reaction.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

scholarly journals Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

2016 ◽  
Vol 12 ◽  
pp. 2588-2601 ◽  
Author(s):  
Vladimir A Stepchenko ◽  
Anatoly I Miroshnikov ◽  
Frank Seela ◽  
Igor A Mikhailopulo
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Reaction Conditions ◽  
E Coli ◽  
No Formation ◽  
Structural Peculiarities ◽  
Substrate Properties ◽  
Nucleoside Phosphorylases ◽  
Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

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