共查询到20条相似文献,搜索用时 31 毫秒
1.
Wen-Sheng C. Yi L. Chuan-Pei Z. Qiang-Guo L. Song-Sheng Q. 《Journal of Thermal Analysis and Calorimetry》2003,73(1):285-291
The solid-state coordination reactions of lanthanum chloride with alanine and glycine, and lanthanum nitrate with alanine
have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in
2 mol L-1 HCl solvent of these three solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the
results and other auxiliary quantities, the standard molar formation enthalpies have been determined to be Δf
H
m
θ[La(Ala)3Cl3·3H2O(s), 298.2 K]= -3716.3 kJ mol-1, Δf
H
m
θ [La(Gly)3Cl3·5H2O(s), 298.2 K]= -4223.0 kJ mol-1 and Δf
H
m
θ [La(Ala)4(NO3)3·H2O(s), 298.2 K]= -3867.57 kJ mol-1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Huo-Yan Chen Meng Zhao Jia-Heng Tan Zhi-Shu Huang Gao-Feng Liu Liang-Nian Ji Zong-Wan Mao 《Tetrahedron》2014
We reported a novel mono-β-cyclodextrin derivative, mono-6-deoxy-6-biguanidino-β-cyclodextrin (β-biGCD), which was investigated as a mimic of ADP/ATP carrier (AAC). Its affinity toward AMP, ADP, and ATP was evaluated by means of isothermal titration calorimetry (ITC). The association constants (Ka) of β-biGCD binding to AMP, ADP, and ATP were determined to be (1.07±0.04)×106, (5.86±0.02)×106, and (4.33±0.06)×106 L mol−1, respectively, which were 100-fold higher than mono-guanidino-β-cyclodextrin (ca. 104 L mol−1). UV spectroscopic titrations further confirmed the above results. The interaction between β-biGCD and nucleotides was probed by docking simulation. These results reveal that the biguanidinium moiety mimics the arginine residues of mitochondrial AAC protein. 相似文献
3.
Grell D. Grell E. Bugnon P. Dietrich B. Lehn J.-M. 《Journal of Thermal Analysis and Calorimetry》2004,77(2):483-495
The coordination of divalent and monovalent inorganic anions to synthetic polyammonium receptors is investigated in aqueous
solution around neutral pH by titration calorimetry and NMR spectroscopy. High-affinity 1:1 complexes are formed by a pyrrole
type cryptand (1) with sulfate and phosphate, characterized by association constants of almost 107 M-1. Affinities close to 105 M-1 are found for polyazacryptands (3 and 4) exhibiting F-/Cl- selectivity. The binding affinities and the anion selectivities are mainly caused by the charges of ligands and anions, which
is discussed on the basis of simple calculations of the electrostatic contribution to the anion/receptor interactions. The
binding of all investigated anions is exothermic at 298.2 K. The contribution of the large negative ΔH values to the free
energy of anion binding of the pyrrole type ligand is partially compensated by marked negative ΔS values. These unfavorable
entropic contributions are attributed to the additional inclusion of water molecules in the anion/receptor complexes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Ofloxacin is an antibacterial compound that belongs to the fluoroquinolone family. In this paper, the interaction between
ofloxacin and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and UV-Vis absorbtion spectroscopy
under approximately the human physiological conditions. The thermodynamic parameters were calculated according to the dependence
of enthalpy change on the temperature as follows: ΔH has a small negative value (−9.96 kJ⋅mol−1), whereas ΔS has a positive value (54.77 J⋅mol−1⋅K−1). In this work, it was proved that the fluorescence quenching of BSA by ofloxacin is a result of the formation of an ofloxacin–BSA
complex. Binding studies concerning the number of binding sites (n=1.14) and apparent binding constant were performed by Scatchard’s procedure. The binding distance r between donor (BSA) and acceptor (ofloxacin) was obtained according to the fluorescence resonance energy transfer (FRET)
method. 相似文献
5.
利用亲和毛细管电泳(Affinitycapillaryelectrophoresis,ACE)法研究金属元素组和血清白蛋白(Bovineserumalbumin,BSA)的竞争结合反应性能。基于位点结合模型,构建双金属组[Zn2+,Cu2+]与血清白蛋白结合反应模型,建立多元金属组与生物大分子竞争结合的理论方程,测定结合参数并解析动力学机制。结果表明,金属元素组[Zn2+,Cu2+]与BSA发生竞争结合反应形成配合物Zn2+-BSA和Cu2+-BSA。依据有效淌度变化,通过建立的理论方程非线性拟合竞争结合反应的平均表观结合常数KZn2+-BSA=4.01×104L·mol-1、KCu2+-BSA=7.75×104L·mol-1。结合反应均为快平衡反应,Cu2+对Zn2+离子的结合作用有明显拮抗作用。分析ACE谱显示配合物的峰高与配体结合能力大小、配合物稳定性之间存在量效关系。 相似文献
6.
利用亲和毛细管电泳(Affinity capillary electrophoresis,ACE)法研究金属元素组和血清白蛋白(Bovine serum albumin,BSA)的竞争结合反应性能。基于位点结合模型,构建双金属组[Zn2+,Cu2+]与血清白蛋白结合反应模型,建立多元金属组与生物大分子竞争结合的理论方程,测定结合参数并解析动力学机制。结果表明,金属元素组[Zn2+,Cu2+]与BSA发生竞争结合反应形成配合物Zn2+-BSA和Cu2+-BSA。依据有效淌度变化,通过建立的理论方程非线性拟合竞争结合反应的平均表观结合常数KZn2+-BSA=4.01×104L·mol-1、KCu2+-BSA=7.75×104L·mol-1。结合反应均为快平衡反应,Cu2+对Zn2+离子的结合作用有明显拮抗作用。分析ACE谱显示配合物的峰高与配体结合能力大小、配合物稳定性之间存在量效关系。 相似文献
7.
Wenshen C. Yi L. Chuanpei Z. Songsheng Q. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):463-468
The solid-state coordination reaction: Nd(NO3)3·6H2O(s)+4Ala(s) → Nd(Ala)4(NO3)3·H2O(s)+5H2O(l) and Er(NO3)3·6H2O(s)+4Ala(s) → Er(Ala)4(NO3)3·H2O(s)+5H2O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products
in 2 mol L–1 HCl solvent of
these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary
quantities, the standard molar formation enthalpies of [Nd(Ala)4(NO3)3·H2O, s, 298.2 K] and[Er(Ala)4(NO3)3·H2O, s,298.2 K] at 298.2 K have been determined to be Δf
H
m
0 [Nd(Ala)4(NO3)3·H2O,s, 298.2 K]=–3867.2 kJ mol–1, and Δf
H
m
0 [Er(Ala)4(NO3)3·H2O, s, 298.2 K]=–3821.5 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
The interaction between apigenin (Ap) and bovine serum albumin (BSA) in physiological buffer (pH = 7.4) is investigated by
fluorescence quenching technique and UV-vis absorption spectra. The results reveal that Ap could strongly quench the intrinsic
fluorescence of BSA. The quenching mechanism of Ap for BSA varies with the change of Ap concentration. when Ap concentration
is lower, it is a static quenching procedure, when Ap concentration is higher, a combined quenching (both static and dynamic)
would operate. The apparent binding constants Ka and number of binding sites n of Ap with BSA are obtained by fluorescence
quenching method. The thermodynamic parameters, enthalpy change (Δr
H
m
and entropy change (Δr
S
m
), are calculated to be −15.382 kJ mol−1 K−1 < 0 and 104.888 J mol−1 K−1 > 0, respectively, which indicate that the interaction of Ap with BSA is driven mainly by hydrogen bonding and hydrophobic
interactions. The distance r between BSA and Ap is calculated to be 1.89 nm based on F?rster’s non-radiative energy transfer theory. The results of synchronous
fluorescence spectra show that binding of Ap with BSA cannot induce conformational changes in BSA. 相似文献
9.
Zhiyan Song Kari J. Parker Idorenyin Enoh Hua Zhao Olarongbe Olubajo 《Magnetic resonance in chemistry : MRC》2010,48(2):123-128
Interaction of polyamines with nucleotides plays a key role in many biological processes. Here we use multiple NMR techniques to characterize interaction of spermidine with adenosine 5′‐triphosphate (ATP). Two‐dimensional 1H‐15N spectra obtained from gs‐HMBC experiments at varied pH show significant shift of N‐1 peak around pH 2.0–7.0 range, suggesting that spermidine binds to N‐1 site of ATP base. The binding facilitates N‐1 deprotonation, shifting its pKa from 4.3 to 3.4. By correlating 15N and 31P chemical shift data, it is clear that spermidine is capable of concurrently binding to ATP base and phosphate sites around pH 4.0–7.0. The self‐diffusion constants derived from 1H PFG‐diffusion measurements provide evidence that binding of spermidine to ATP is in 1:1 ratio, and pH variations do not induce significant nucleotide self‐association in our samples. 31P spectral analysis suggests that at neutral pH, Mg2+ ion competes with spermidine and shows stronger binding to ATP phosphates. From 31P kinetic measurements of myosin‐catalyzed ATP hydrolysis, it is found that binding of spermidine affects the stability and reactivity of ATP. These NMR results are important for advancing the studies on nucleotide–polyamine interaction and its impact on nucleotide structures and activities under varied conditions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
P. Wang J. L. Oscarson R. M. Izatt G. D. Watt C. D. Larsen 《Journal of solution chemistry》1995,24(10):989-1012
The interaction of adenosine 5-diphosphate (ADP) and adenosine 5-triphosphate (ATP) with Mg2+ in water has been studied calorimetrically at 323.15, 348.15, 373.15, and 398.15 K for ATP and at 348.15 and 373.15 K for ADP. The enthalpies of reaction of Mg2+ with ADP and ATP were obtained from the heats of mixing of aqueous solutions of tetramethylammonium salts of ADP and ATP with MgCl2 solutions in an isothermal flow calorimeter. Equilibrium constant (K), enthalpy change (H°), entropy change (S°), and heat capacity change (Cp°) values were calculated for the interaction: Mg2++Ln–=MgL2–n and Mg2++MgL2–n=Mg2L4–n, where n=4 for L=ATP and n=3 for L=ADP. The results are consistent with those at lower temperatures. For the two nucleotides studied, the above two reactions are endothermic and entropy-driven in the temperature range studied. Large Cp° values for the interaction of Mg2+ with ADP with ATP indicate the involvement of phosphate groups of nucleotides in the coordination of Mg2+. The coordination of the first and second Mg2+ ions involves the phosphate chain in both ADP and ATP. No evidence was found for the involvement of the adenine ring or the ribose moiety in the coordination of Mg2+ with these nucleotides. Approximate values of logK, H°, and S°, and Cp° for the self-association of ADP and ATP in the presence of Mg2+ are also given. 相似文献
11.
M. M. Saeed M. M. Saeed R. Ahmed R. Ahmed 《Journal of Radioanalytical and Nuclear Chemistry》2005,267(1):147-153
Summary The sorption of Eu(III) ions onto PAN loaded PUF has been optimized and investigated under the influence of various temperatures,
i.e., 303, 313 and 323 K. Maximum retention (>96%) of Eu(III) ions (1.79. 10-5M) onto PAN loaded PUF (7.75 mg. ml-1) was achieved after 30-minute equilibration time from pH 7 buffer solution. The variation of sorption with temperature yields
the thermodynamic parameters ΔH=79±2 kJ. mol-1, ΔS=276±7 kJ. mol-1. K-1and ΔG=-1.4±0.1 kJ. mol-1at 298 K. The positive value of enthalpy and negative free energy show endothermic and spontaneous nature of sorption, respectively.
The sorption data followed Freundlich, Dubinin-Radushkevich (D-R) and Langmuir isotherms at all the three given temperatures.
The Freundlich constant 1/n=0.70, 0.62 and 0.55 and sorption capacities Cm=10.8 mmol. g-1, 6.1 mmol. g-1and 4.4 mmol. g-1, respectively, decreased with increasing temperature. Similarly, the sorption capacities of D-R isotherm Xm=197.6 μmol. g-1, 201.2 μmol. g-1and 137.4 μmol. g-1, also decreased with temperature. However, the sorption free energy E=10.2 kJ. mol-1, 11.2 kJ. mol-1and 12.7 kJ. mol-1, increased with temperature. The monolayer coverage (Q) computed from Langmuir isotherm was 11.1±0.6 μmol. g-1and remains constant at all the three temperatures investigated. However, the binding energy constant bincreased with temperature. The relationship of bwith temperature and differential heat of adsorption (ΔHdiff) have been evaluated and discussed. 相似文献
12.
G. Rezaei Behbehani A. A. Saboury A. Fallah Baghery 《Journal of solution chemistry》2007,36(10):1311-1320
The interaction of myelin basic protein (MBP) from the bovine central nervous system with divalent calcium ion was studied
by isothermal titration calorimetry at 27 °C in aqueous solution. The extended solvation model was used to reproduce the enthalpies
of Ca2+-MBP interaction over the whole range of Ca2+ concentrations. The solvation parameters recovered from the solvation model were attributed to the structural change of MBP
due to the metal ion interaction. It was found that there is a set of two identical and non-interacting binding sites for
Ca2+ ions. The association equilibrium constant is 0.021 μmol⋅dm−3. The molar enthalpy of binding is ΔH=−15.10 kJ⋅mol−1. 相似文献
13.
HE Wenying YAO Xiaojun LIU Pengjun GAO Zhenxia & HU Zhide . Department of Chemistry Lanzhou University Lanzhou China . Department of Chemistry Hainan Normal University Hainan China 《中国科学B辑(英文版)》2006,49(6):550-559
The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes. 相似文献
14.
Rajendran Senthil Kumar Hubert van?den Bergh Georges Wagnières 《Journal of solution chemistry》2012,41(2):294-306
The mechanism of binding of the surfactant–cobalt(III) complex, cis-[Co(phen)2(C14H29NH2)Cl](ClO4)2⋅3H2O (phen = 1,10-phenanthroline, C14H29NH2 = tetradecylamine) with bovine serum albumin (BSA) was investigated by UV–vis absorption, circular dichroism (CD) and fluorescence
spectroscopic techniques. The results of fluorescence titration revealed that the surfactant–cobalt(III) complex quenched
the intrinsic fluorescence of BSA through a combination of static and dynamic quenching. The apparent binding constant (K
a) and number of binding sites (n) were calculated below and above the critical micelle concentration (CMC). The thermodynamic parameters determined by the
van’t Hoff analysis of the constants (ΔH
∘=14.87 kJ⋅mol−1; ΔS
∘=152.88 J⋅mol−1⋅K−1 below the CMC and 25.70 kJ⋅mol−1 and 243.14 J⋅mol−1⋅K−1, respectively, above the CMC) clearly indicate that the binding is entropy-driven and enthalpically disfavored. Based on
F?rster’s theory of non-radiation energy transfer, the binding distance, r, between donor (BSA) and the acceptor (surfactant–cobalt(III) complex) was evaluated. UV–vis, CD and synchronous fluorescence
spectral results showed that the binding of the surfactant–cobalt(III) complex to BSA induced conformational changes in BSA. 相似文献
15.
G. Rezaei Behbehani A. A. Saboury A. Fallah Baghery A. Abedini 《Journal of Thermal Analysis and Calorimetry》2008,93(2):479-483
Binding properties of myelin basic protein (MBP) from bovine central nervous system due to the interaction by divalent magnesium
ion (Mg2+) was investigated at 27°C in aqueous solution using isothermal titration calorimetry (ITC) technique. An extended solvation
model was used to reproduce the enthalpies of Mg2+-MBP interaction over the whole Mg2+ concentrations. It was found that there is a set of two identical and noninteracting binding sites for Mg2+ ions. The dissociation equilibrium constant is K
d=45.5 μM. The molar enthalpy of binding site is identical for both sites; ΔH=−15.24 kJ mol−1. The solvation parameters recovered from the solvation model were attributed to the structural change of MBP due to the metal
ion interaction. 相似文献
16.
Polymorphism of paracetamol 总被引:1,自引:0,他引:1
G. L. Perlovich Tatyana V. Volkova Annette Bauer-Brandl 《Journal of Thermal Analysis and Calorimetry》2007,89(3):767-774
The thermodynamic relationship between crystal modifications of paracetamol was studied by alternative methods. Temperature
dependence of saturated vapor pressure for polymorphic modifications of the drug paracetamol (acetaminophen) was mea sured
and thermodynamic functions of the sublimation process calculated. Solution calorimetry was carried out for the two modifications
in the same solvent. Thermodynamic parameters for sublimation for form I (monoclinic) were found: ΔG
sub298=60.0 kJ mol−1; ΔH
sub298=117.9±0.7 kJ mol−1; ΔS
sub298=190±2 J mol−1 K−1. For the orthorhombic modification (form II), the saturated vapor pressure could only be studied at 391 K. Phase transition
enthalpy at 298 K, ΔH
tr298(I→II)=2.0±0.4 kJ mol−1, was derived as the difference between the solution enthalpies of the noted polymorphs in the same solution (methanol). Based
on ΔH
tr298 (I→II), differences between temperature dependencies of heat capacities of both modifications and the vapor pressure value
of form II at 391 K, the temperature dependence of saturated vapor pressure and thermodynamic sublimation parameters for modification
II were also estimated (ΔG
sub298=56.1 kJ mol−1; ΔH
sub298=115.9±0.9 kJ mol−1; ΔS
sub298=200±3 J mol−1 K−1). The results indicate that the modifications are monotropically related, which is in contrast to findings recently reported
found by classical thermochemical methods. 相似文献
17.
Tian J. Han S. C. Zeng H. H. Wang B. H. Li Z. F. Zhang Y. M. 《Journal of Thermal Analysis and Calorimetry》1998,54(3):775-783
Microcalorimetric measurements of the polymerization of actin in the presence of 100 mM KCl and 2 mM MgCl2were carried out with a Calvet MS-80 microcalorimeter at temperatures from 293.15 to 310.15 K. It was observed that the polymerization
of actin was endothermic and the enthalpy change for actin polymerization was temperature-dependent. The enthalpy change ΔHowas fitted to ΔHo(kJ mol-1)=434.0-1.16 (T/K) and the change in heat capacity ΔCp
ocalculated from ΔHowas -1.16 kJ (mol K)-1in the above range of temperatures. The direct calorimetry results showed that the enthalpy and entropy change for actin polymerization
could not be obtained from measurements of the critical concentration and the only way to assess the enthalpy change for the
polymerization of actin and similar reactions lies in the use of calorimetry.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
N. I. Boiko R. I. Zhdanov E. P. Dyachkov P. N. Dyachkov 《Russian Chemical Bulletin》2008,57(8):1775-1778
Calculations by molecular mechanics methods showed that diglycerides containing stearic, oleic, linoleic, or linolenic acids
can bind to DNA. The binding energy of diglycerides to the DNA minor groove is higher than that to the major groove. The bond
energies of diglycerides to DNA were calculated as the sums of the contributions of the binding energies between DNA and two
fatty acid residues. These energies depend on the structure of the fatty acid and the nucleotide composition of DNA and vary
from 20 to 120 kcal mol−1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1741–1744, August, 2008. 相似文献
19.
Gholamreza Rezaei Behbehani Ali A. Saboury Maryam Mohebbian Sanaz Tahmasebi Mohammadfeza Poorheravi 《Journal of solution chemistry》2009,38(12):1612-1621
The cyanide ion was studied as an effecter of Jack bean urease at 300 K in 30 mmol⋅L−1 Tris buffer, pH=7. The inhibition was investigated by isothermal titration calorimetry (ITC). The extended solvation model
was used for CN−+JBU interaction over the whole range of CN− concentrations. The binding parameters recovered from the solvation model were attributed to the interaction with cyanide
ion. It was found that cyanide ion acted as a noncooperative inhibitor of urease, and there is a set of 12 identical and independent
binding sites for CN− ions. The dissociation equilibrium constant is 749.99 μmol⋅L−1. The molar enthalpy of binding is ΔH=−13.60 kJ⋅mol−1. 相似文献
20.
Javed MR Rashid MH Nadeem H Riaz M Perveen R 《Applied biochemistry and biotechnology》2009,157(3):483-497
Monomeric extracellular endoglucanase (25 kDa) of transgenic koji (Aspergillus oryzae cmc-1) produced under submerged growth condition (7.5 U mg−1 protein) was purified to homogeneity level by ammonium sulfate precipitation and various column chromatography on fast protein
liquid chromatography system. Activation energy for carboxymethylcellulose (CMC) hydrolysis was 3.32 kJ mol−1 at optimum temperature (55 °C), and its temperature quotient (Q
10) was 1.0. The enzyme was stable over a pH range of 4.1–5.3 and gave maximum activity at pH 4.4. V
max for CMC hydrolysis was 854 U mg−1 protein and K
m was 20 mg CMC ml−1. The turnover (k
cat) was 356 s−1. The pK
a1 and pK
a2 of ionisable groups of active site controlling V
max were 3.9 and 6.25, respectively. Thermodynamic parameters for CMC hydrolysis were as follows: ΔH* = 0.59 kJ mol−1, ΔG* = 64.57 kJ mol−1 and ΔS* = −195.05 J mol−1 K−1, respectively. Activation energy for irreversible inactivation ‘E
a(d)’ of the endoglucanase was 378 kJ mol−1, whereas enthalpy (ΔH*), Gibbs free energy (ΔG*) and entropy (ΔS*) of activation at 44 °C were 375.36 kJ mol−1, 111.36 kJ mol−1 and 833.06 J mol−1 K−1, respectively. 相似文献