scholarly journals Spectroscopic and Electrochemical Studies on the Interaction of Epirubicin with Fish Sperm DNA

2012 ◽  
Vol 9 (3) ◽  
pp. 1587-1598 ◽  
Author(s):  
R. Hajian ◽  
E. Ekhlasi ◽  
R. Daneshvar
Keyword(s):  
Cyclic Voltammetry ◽  
Thermodynamic Parameters ◽  
Strong Interactions ◽  
Binding Force ◽  
Double Stranded Dna ◽  
Fish Sperm ◽  
Sperm Dna ◽  
Apparent Binding Constant ◽  
Different Temperatures ◽  
Voltammetric Behavior

The interactions between epirubicin (EPR) and double stranded DNA (ds-DNA) have been studied by UV-Vis spectrophotometry, cyclic voltammetry, fluorescence spectroscopy and viscometery. The apparent binding constant of epirubicin with DNA was found to be 3.8 × 105mol-1L and was studied at different temperatures. It indicated that the former method could be successfully applied to the determination of epirubicin. Also, the voltammetric behavior of EPR was investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including ∆H0, ∆G0and ∆S0were determined as -5.7×104, -3.13×104J mol-1and -87.96 J mol-1K-1 respectively. One indication of the strong interaction between DNA and EP was increasing of viscosity. The diffusion coefficients of EP in the absence (D0)fand presence of ds-DNA (D0)bwas calculated as 5.04×10-6and 1.13×10-6 Cm2s-1respectively. According to the thermodynamic parameters, the main binding force could be judged. The experimental results revealed that EPR and ds-DNA had strong interactions. The mechanism of quenching belonged to static quenching and the main sort of binding force was intercalation.

scholarly journals Thermodynamic and detailed kinetic study of the formation of orthophthalaldehyde-agmatine complex by fluorescence intensities

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Khémesse Kital ◽  
Moumouny Traoré ◽  
Diégane Sarr ◽  
Moussa Mbaye ◽  
Mame Diabou Gaye Seye ◽  
...  
Keyword(s):  
Complex Formation ◽  
Thermodynamic Parameters ◽  
Initial Rate ◽  
Reaction Medium ◽  
Standard Entropy ◽  
Step Size ◽  
Formation Reaction ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Complex Formation Process

Abstract The aim of this work is to determine the thermodynamic parameters and the kinetics of complex formation between orthophthalaldehyde (OPA) and agmatine (AGM) in an alkaline medium (pH 13). Firstly, the association constant (Ka) between orthophthalaldehyde and agmatine was determined at different temperatures (between 298 K and 338 K) with a step size of 10 K. Secondly, the thermodynamic parameters such as standard enthalpy (ΔH°), standard entropy (ΔS°),and Gibbs energy (∆G) were calculated, where a positive value of ΔH° (+45.50 kJ/mol) was found, which shows that the reaction is endothermic. In addition, the low value of ΔS°(+0.24 kJ/mol) indicates a slight increase in the disorder in the reaction medium. Furthermore, the negative values of ΔG between −35.62 kJ/mol and −26.02 kJ/mol show that the complex formation process is spontaneous. Finally, the parameters of the kinetics of the reaction between OPA and AGM were determined as follows: when the initial concentration of AGM (5 × 10−6 M) is equal to that of the OPA, the results show that the reaction follows an overall 1.5 order kinetics with an initial rate of 5.1 × 10−7Mmin−1 and a half-life of 8.12 min. The partial order found in relation to the AGM is 0.8. This work shows that the excess of OPA accelerates the formation reaction of the complex.

scholarly journals Thermodynamic studies of substrate binding and spin transitions in human cytochrome P-450 3A4 expressed in yeast microsomes

1996 ◽  
Vol 319 (3) ◽  
pp. 675-681 ◽  
Author(s):  
Jean-Paul RENAUD ◽  
Dmitri R. DAVYDOV ◽  
Karel P. M. HEIRWEGH ◽  
Daniel MANSUY ◽  
Gaston HUI BON HOA
Keyword(s):  
Thermodynamic Parameters ◽  
Protein Interactions ◽  
Substrate Binding ◽  
Principal Component ◽  
Yeast Saccharomyces Cerevisiae ◽  
Human Cytochrome ◽  
Different Temperatures ◽  
Haem Protein ◽  
Cytochrome P 450 ◽  
Spin Transitions

An approach to the quantitative spectral analysis of substrate binding and inactivation of cytochrome P-450 in microsomes is described. The method is based on the application of the principal component analysis technique on the Soret-region spectra measured at different temperatures at various concentrations of substrate. This approach allowed us to study the thermodynamic parameters of substrate binding and spin transitions in human cytochrome P-450 3A4 expressed in yeast (Saccharomyces cerevisiae) microsomes. These parameters are discussed in comparison with the values reported earlier by Ristau et al. [(1979) Acta Biol. Med. Ger. 38, 177–185] for rabbit liver cytochrome P-450 2B4 in solution with benzphetamine as a substrate. Our analysis shows the substrate-free states of 2B4 and 3A4 to be very similar. However, substrate binding seems to perturb haem-protein interactions in 3A4 in contrast with 2B4, where the effect of substrate binding on the thermodynamic parameters of spin transitions was insignificant. The implication of the results for the mechanism of substrate-induced spin shift is discussed.

scholarly journals Changes in the Level of DNA Fragmentation in Sperm Cells detected by Acridine Orange Test in Men with Sub/infertility Treated with Nutritional Supplement PAPA

Folia Medica ◽  
2020 ◽  
Vol 62 (1) ◽  
pp. 112-116
Author(s):  
Stoil N. Tomov ◽  
Radoslava St. Stoyanova ◽  
Pepa K. Atanasova ◽  
Ivan Y. Dechev
Keyword(s):  
Acridine Orange ◽  
Dna Fragmentation ◽  
Physiological Condition ◽  
Nutritional Supplement ◽  
Sperm Cells ◽  
Sperm Dna Fragmentation ◽  
Double Stranded Dna ◽  
Sperm Dna ◽  
Before And After ◽  
Sperm Nuclei

Background: When diagnosing and treating male infertility it is important to determine whether there are defects in the maturation process of sperm nuclei. Using nutritional supplements can improve the morphological and physiological condition of the spermatozoa. In recent years there has been an increase in the usage of supplements with different compositions which strives to determine the best combination and avoid side effects. &nbsp; Aim: To study the effect of PAPA nutritional supplement on the levels of DNA fragmentation of sperm cells tested with acridine orange test (single stranded DNA against double stranded DNA) in men with sub/infertility. &nbsp; Materials and methods: 48 men with confirmed sub/infertility underwent treatment for three months with nutritional supplement PAPA containing 9 micronutrients. The differences in levels of DNA fragmentation were determined with acridine orange test, which was conducted before and after the treatment. &nbsp; Results: The results were statistically significant (p<0.001) showing an increase in the number of green spermatozoa (normal DNA), and a decrease of damaged ones (orange and red). After treatment the level of sperm DNA fragmentation decreased by 10.2%. &nbsp; Conclusion: Men with confirmed sub/infertility that took nutritional supplement PAPA for three moths showed a decrease in DNA fragmentation levels of 10.2% determined by AO test which implies an improvement of male fertility levels.

scholarly journals Enhancing the Ethynylation Performance of CuO-Bi2O3 Nanocatalysts by Tuning Cu-Bi Interactions and Phase Structures

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 35 ◽  
Author(s):  
Zhipeng Wang ◽  
Zhuzhu Niu ◽  
Quanai Hao ◽  
Lijun Ban ◽  
Haitao Li ◽  
...  
Keyword(s):  
Industrial Applications ◽  
Strong Interactions ◽  
Catalytic Systems ◽  
Key Factor ◽  
Different Temperatures ◽  
Catalytic Stability ◽  
Phase Spinel ◽  
Co Precipitation ◽  
Catalytic Cycles ◽  
Cu Ions

Catalytic systems consisting of copper oxide and bismuth oxide are commonly employed for the industrial production of 1,4-butynediol (BD) through ethynylation. However, few studies have investigated the influence mechanism of Bi for these Cu-based catalysts. Herein, a series of nanostructured CuO-Bi2O3 catalysts were prepared by co-precipitation followed by calcination at different temperatures. The obtained catalysts were applied to the ethynylation reaction. The textural and crystal properties of the catalysts, their reduction behavior, and the interactions between copper and bismuth species, were found to strongly depend on temperature. When calcined at 600 °C, strong interactions between Cu and Bi in the CuO phase facilitated the formation of highly dispersed active cuprous sites and stabilized the Cu+ valency, resulting in the highest BD yield. Bi2O3 was completely absent when calcined at 700 °C, having been converted into the spinel CuBi2O4 phase. Spinel Cu2+ was released gradually to form active Cu+ species over eight catalytic cycles, which continuously replenished the decreasing activity resulting from the formation of metallic Cu and enhanced catalytic stability. Moreover, the positive correlation between the in-situ-formed surface Cu+ ions and BD yield suggests that the amount of Cu+ ions is the key factor for ethynylation of formaldehyde to BD on the as prepared CuO-Bi2O3 catalysts. Based on these results and the literature, we propose an ethynylation reaction mechanism for CuO-based catalysts and provide a simple design strategy for highly efficient catalytic CuO-Bi2O3 systems, which has considerable potential for industrial applications.

The Effect of Ru on Unsupported Pt-Ru Alloys for Methanol Electro-Oxidation at Different Temperatures

1995 ◽  
Vol 393 ◽  
Author(s):  
Deryn Chu ◽  
Charles Walker ◽  
Sol Gilman
Keyword(s):  
Cyclic Voltammetry ◽  
Sulfuric Acid ◽  
Surface Area ◽  
Hydrogen Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Adsorption Surface ◽  
Electro Oxidation ◽  
Bulk Alloys

ABSTRACTUnsupported different atomic ratios of platinum-ruthenium bulk alloys were prepared. The alloys were characterized by cyclic voltammetry, X-ray diffraction and energy dispersive X-ray spectroscopy. These alloys were also tested as anodes for methanol electro-oxidation in sulfuric acid over a range of temperatures. Ruthenium is inactive for methanol electro-oxidation at 25 °C, but becomes active at higher temperatures. When a comparison is made on the basis of “true” (hydrogen adsorption) surface area, a 30 atomic percent Ru electrocatalyst provides the highest activity for methanol electro-oxidation as measured at either 0.4 or 0.5V vs. RHE at both 25 and 60 °C.

Study on the Stability of all Vanadium Redox Flow Battery Electrolyte

2013 ◽  
Vol 281 ◽  
pp. 461-464
Author(s):  
Shu Di Zhang ◽  
Yu Chun Zhai
Keyword(s):  
Cyclic Voltammetry ◽  
Quantitative Analysis ◽  
Ammonium Oxalate ◽  
Vanadium Redox Flow Battery ◽  
Sodium Oxalate ◽  
Redox Flow Battery ◽  
Different Temperatures ◽  
Battery Electrolyte ◽  
The Stability ◽  
Vanadium Redox

In order to study on several additives to Vanadium battery electrolyte stability, different additives were added in the electrolyte of vanadium battery electrolyte at different temperatures, precipitation time were observed, cyclic voltammetry curves were tested and ultraviolet quantitative analysis to precipitated supernatant , The results show that after adding the different additives, at 40 °C temperature, 1.8 mol / L concentration can stably exist in the electrolyte of the vanadium battery. The added amount of sodium oxalate, ammonium oxalate is equivalent 3% of the amount V4+ solution, the vanadium battery electrolyte stability can be improved without affecting its reversible reaction, it is a preferred stabilizer.

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