Ethidium Bromide Interaction with Poly(G)

In current work we investigate the interaction between polyguanylic acid and Ethidium Bromide ( EtBr ) and the changes of thermodynamic parameters due to those interactions by spectrophotometric methods. From the binding isotherms, binding constants were calculated for three different temperatures and the changes of Gibbs free energy, entropy and enthalpy for complex-formation were determined. Complex-formation with four-stranded poly(G) structure needs less conformational changes in contrast with poly(G)poly(C), and due to that, EtBr binds with 5 and not 4 nucleotides. Obtained results confirm the concept that polyguanylic acids may form four-stranded complex structures with intercalating ligand EtBr in the aqueous solution.

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Morphological Analysis and Interaction of Chlorophyll and BSA

BioMed Research International ◽

10.1155/2014/872701 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 5

Author(s):

Filipe D. S. Gorza ◽

Graciela C. Pedro ◽

Tarquin F. Trescher ◽

Romário J. da Silva ◽

Josmary R. Silva ◽

...

Keyword(s):

Conformational Changes ◽

Morphological Analysis ◽

Protein Complexes ◽

Binding Constants ◽

Blood Stream ◽

Fractal Structures ◽

Free Concentration ◽

Different Temperatures ◽

Order Of Magnitude ◽

Uv Visible

Interactions between proteins and drugs, which can lead to formation of stable drug-protein complexes, have important implications on several processes related to human health. These interactions can affect, for instance, free concentration, biological activity, and metabolism of the drugs in the blood stream. Here, we report on the UV-Visible spectroscopic investigation on the interaction of bovine serum albumin (BSA) with chlorophyll (Chl) in aqueous solution under physiological conditions. Binding constants at different temperatures—obtained by using the Benesi-Hildebrand equation—were found to be of the same order of magnitude (~104 M−1) indicating low affinity of Chl with BSA. We have found a hyperchromism, which suggested an interaction between BSA and Chl occurring through conformational changes of BSA caused by exposition of tryptophan to solvent. Films from BSA and Chl obtained at different Chl concentrations showed fractal structures, which were characterized by fractal dimension calculated from microscopic image analysis.

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The effect of temperature on tight metal binding by peat and soil derived solid humic acids

Canadian Journal of Soil Science ◽

10.4141/s00-065 ◽

2001 ◽

Vol 81 (3) ◽

pp. 331-336 ◽

Cited By ~ 8

Author(s):

Elham A Ghabbour ◽

Geoffrey Davies ◽

Nadeem K Ghali ◽

Matthew D Mulligan

Keyword(s):

Humic Acids ◽

Conformational Changes ◽

Metal Binding ◽

Equilibrium Constants ◽

Tight Binding ◽

Metal Cations ◽

Effect Of Temperature ◽

Binding Isotherms ◽

Different Temperatures ◽

Binding Enthalpy

The brown biomaterials called humic acids (HA) in peats and soils retain water and bind metal cations and other solutes. Studies of the interactions of purified solid peat and soil-derived HA from different countries with metal cations in water probe HA microstructures and help to characterize the metal binding sites. Labile cations such as Caaq2+, Co aq2+, Cu aq2+, Fe aq3+, Mg aq2+ and Mn aq2+ tightly bind to solid HAs in sequential steps. The isotherms A vs. c are well fitted with the Langmuir model and plots of 1/A vs. 1/c are linear for each step. Here, A is mmol bound metal g–1 HA and c is the equilibrium cation concentration (M). This paper compares the stoichiometric site capacities vi and equilibrium constants Ki for tight binding of Ca aq2+, Co aq2+, Cu aq2+, Fe aq3+, Mg aq2+ and Mn aq2+ at different solid HA sites. Measurements at different temperatures give linearly correlated metal binding enthalpy and entropy changes, indicating that conformational changes and cation/HA hydration/dehydration are important factors in metal binding and release by solid HAs. Key words: Humic acids; metal binding; isotherms; thermodynamics

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Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. Agha ◽

R. B. R. Persson

Keyword(s):

Complex Formation ◽

Significant Influence ◽

Room Temperature ◽

Ph Value ◽

Maximum Activity ◽

Reduction Step ◽

Labelling Yield ◽

Different Temperatures ◽

Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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Conformational changes in cytochrome c directed by ethylene glycol accompanying complex formation: Protein-solvent preferential interaction or/and kosmotropic effect

Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy ◽

10.1016/j.saa.2020.118788 ◽

2020 ◽

Vol 242 ◽

pp. 118788

Author(s):

Zahoor Ahmad Parray ◽

Faizan Ahmad ◽

Md. Imtaiyaz Hassan ◽

Asimul Islam

Keyword(s):

Cytochrome C ◽

Complex Formation ◽

Ethylene Glycol ◽

Conformational Changes ◽

Preferential Interaction

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Impact of Deuteration and Temperature on Furan Ring Dynamics

Molecules ◽

10.3390/molecules26102889 ◽

2021 ◽

Vol 26 (10) ◽

pp. 2889

Author(s):

Przemyslaw Dopieralski ◽

Iryna V. Omelchenko ◽

Zdzislaw Latajka

Keyword(s):

Conformational Changes ◽

Furan Ring ◽

Computational Studies ◽

Significant Progress ◽

Dynamic Simulations ◽

Cyclic Molecules ◽

Ring Dynamics ◽

Different Temperatures ◽

Long Time ◽

Shape And Size

Despite significant progress in conformational analysis of cyclic molecules, the number of computational studies is still limited while most of that available in the literature data have been obtained long time ago with outdated methods. In present research, we have studied temperature driven conformational changes of the furan ring at three different temperatures. Additionally, the effect of deuteration on the ring dynamics is discussed; in addition, the aromaticity indices following the Bird and HOMA schemes are computed along all trajectories. Our ab initio molecular dynamic simulations revealed that deuteration has changed the furan ring dynamics and the obvious consequences; in addition, the shape and size of molecule are expected to be different.

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Volumetric and acoustic investigation of L-leucine and N-acetyl L-leucine in the aqueous solution of 1-hexyl-3-methylimidazolium bromide [HMIm] [Br] at different temperatures

The Journal of Chemical Thermodynamics ◽

10.1016/j.jct.2021.106452 ◽

2021 ◽

pp. 106452

Author(s):

Harsh Kumar ◽

Ravinder Sharma ◽

Vaneet Kumar ◽

Najla Saad Almasoud

Keyword(s):

Aqueous Solution ◽

Different Temperatures

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

Journal of Analytical Science & Technology ◽

10.1186/s40543-020-00238-2 ◽

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.

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