共查询到20条相似文献,搜索用时 109 毫秒
1.
Sacco C Skowronsky RA Gade S Kenney JM Spuches AM 《Journal of biological inorganic chemistry》2012,17(4):531-541
Metal ions have been shown to play a critical role in β-amyloid (Aβ) neurotoxicity, thus prompting an intense investigation
into the formation of metal–Aβ complexes. Isothermal titration calorimetry (ITC) has been widely used to determine binding
constants (K) for a variety of metal–protein interactions, including those in metal–Aβ complexes. In this study, ITC was used to more
fully quantify the thermodynamics (K, ΔG, ΔH, and TΔS) of Cu2+ binding to Aβ16, N-acetyl-Aβ16, Aβ28, N-acetyl-Aβ28, and Aβ28 variants (H6A, H13A, H14A) at pH 7.4 and 37 °C. After deconvolution of competing reactions, K for Aβ16 was found to be 1.1 (±0.13) × 109 and is in strong agreement with literature values measured under similar conditions. Further, a similar K value was obtained at two additional concentrations of competing ligand, suggesting that ternary complex formation is not
significant. The acetylated peptide analogs reveal a marked decrease in the overall free energy upon binding, which is the
result of less favorable enthalpic and entropic contributions. Circular dichroism spectroscopy shows conformational changes
that are consistent with these results. Most importantly, data for Aβ28 variants lacking a potential Cu2+-binding histidine residue reveal that the overall free energy of binding remains constant, which is the result of entropy/enthalpy
compensation. These data provide fundamental thermodynamic evidence for coordination plasticity in Cu2+ binding to Aβ and other intrinsically disordered peptides. 相似文献
2.
Claudia Hoffmann Alfred Blume Inge Miller Patrick Garidel 《European biophysics journal : EBJ》2009,38(5):557-568
Therapeutic proteins formulated as liquid solutions at high protein concentration are very sensitive to chemical and physical
degradation. Especially avoiding the formation of protein aggregates is very crucial for product quality. In order to stabilize
the colloidal properties of protein therapeutics various excipient are used. Especially the detergents polysorbate 20 and
80 are common. However, the mechanism upon which the detergents protect the protein from aggregation is not really known.
The present study investigates the interaction of polysorbate 20 and 80 with different proteins: lysozyme, bovine serum albumin
(BSA) and an immunoglobulin. The interaction and binding of the detergents to the proteins is investigated by isothermal titration
calorimetry (ITC). From ITC the thermodynamic parameters (ΔH: change in enthalpy, ΔS: entropy and ΔG: free energy) upon binding are derived as well as the binding constant K
a. The thermal stability of the proteins in the presence of the detergent is assessed by differential scanning calorimetry
(DSC). The results show that both detergents bind to BSA with K
a between 8 and 12 × 103 M−1 with ΔH −50 to −60 kJ/mol (25°C). One to two detergent molecules bind to BSA. The presence of both detergents induces a weak stabilisation
of the thermal denaturation properties of BSA. However, the interaction of polysorbate 20 and 80 with lysozyme and the immunoglobulin
is quite negligible. The presence of the detergents up to a concentration of 2 mM has no impact on the heat capacity curve
neither a destabilisation nor a stabilisation of the native conformation is observed. 相似文献
3.
Zohreh Moradi Ali Reza Rezvani Meissam Noroozifar 《Journal of biomolecular structure & dynamics》2018,36(3):779-794
In order to evaluate biological potential of a novel synthesized complex [Nd(dmp)2Cl3.OH2] where dmp is 29-dimethyl 110-phenanthroline, the DNA-binding, cleavage, BSA binding, and antimicrobial activity properties of the complex are investigated by multispectroscopic techniques study in physiological buffer (pH 7.2).The intrinsic binding constant (Kb) for interaction of Nd(III) complex and FS–DNA is calculated by UV–Vis (Kb = 2.7 ± 0.07 × 105) and fluorescence spectroscopy (Kb = 1.13 ± 0.03 × 105). The Stern–Volmer constant (KSV), thermodynamic parameters including free energy change (ΔG°), enthalpy change (?H°), and entropy change (?S°), are calculated by fluorescent data and Vant’ Hoff equation. The experimental results show that the complex can bind to FS–DNA and the major binding mode is groove binding. Meanwhile, the interaction of Nd(III) complex with protein, bovine serum albumin (BSA), has also been studied by using absorption and emission spectroscopic tools. The experimental results show that the complex exhibits good binding propensity to BSA. The positive ΔH° and ?S° values indicate that the hydrophobic interaction is main force in the binding of the Nd(III) complex to BSA, and the complex can quench the intrinsic fluorescence of BSA remarkably through a static quenching process. Also, DNA cleavage was investigated by agarose gel electrophoresis that according to the results cleavage of DNA increased with increasing of concentration of the complex. Antimicrobial screening test gives good results in the presence of Nd(III) complex system. 相似文献
4.
P. V. Ershov O. V. Gnedenko A. A. Molnar A. V. Lisitsa A. S. Ivanov A. I. Archakov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2012,6(1):94-97
The analysis of kinetic and thermodynamic parameters of binding of peptide and nonpeptide dimerization inhibitors of HIV protease
(HIVp) to the enzyme monomers immobilized on an optical chip has been studied by surface plasmon resonance. The molecular
interactions were investigated at different inhibitor concentrations (0–80 μM) and temperatures (15–35°C). Determination of
kinetic (k
on, k
off), equilibrium (K
d), and thermodynamic (ΔG, ΔH, and -TΔS) has shown that both inhibitors are characterized by similar interaction parameters and the entropic term (-TΔS) of about −20 kcal/mol is the main driving force for the HIVp complex formation with the inhibitors, while the positive value
(14 kcal/mol) of the enthalpic term (ΔH) counteracted the complex formation. 相似文献
5.
P. O. Vardevanyan A. P. Antonyan G. A. Manukyan A. T. Karapetyan A. K. Shchyolkina O. F. Borisova 《Molecular Biology》2000,34(2):272-276
Isotherms of the EtBr adsorption on native and denatured poly(dA)poly(dT) in the temperature interval 20–70°C were obtained.
The EtBr binding constants and the number of binding sites were determined. The thermodynamic parameters of the EtBr intercalation
complex upon changes of solution temperature 20–48°C were calculated: 1.0·106 M−1≤K≤1.4·106 M−1, free energy ΔG
o=−8.7±0.3 kcal/mol, enthalpy ΔH
o≅0, and entropy ΔS
o=28±0.5 cal/(mol deg). UV melting has shown that the melting temperature (T
m) of EtBr-poly(dA)poly(dT) complexes (μ=0.022,4.16·10−5 M EtBr) increased by 17°C as compared with the ΔT
m of free homopolymer, whereas the half-width of the transition (T
m) is not changed. It was shown for the first time that EtBr forms complexes of two types on single-stranded regions of poly(dA)poly(dT)
denatured at 70°C: strong (K
1=1.7·105 M−1; ΔG
o=−8.10±0.03 kcal/mol) and weak (K
2=2.9·103 M−1; ΔG
o=−6.0±0.3 kcal/mol).The ΔG
o of the strong and weak complexes was independent of the solution ionic strength, 0.0022≤μ≤0.022. A model of EtBr binding
with single-stranded regions of poly(dA)poly(dT) is discussed. 相似文献
6.
Thomas J. José Lori H. Conlan C. M. Dupureur 《Journal of biological inorganic chemistry》1999,4(6):814-823
19 F NMR spectroscopy have been applied to evaluate metal ion binding by the representative PvuII endonuclease in the absence of substrate. In separate experiments, ITC data demonstrate that PvuII endonuclease binds 2.16 Mn(II) ions and 2.05 Ca(II) metal ions in each monomer active site with K
d values of ≈ 1 mM. While neither calorimetry nor protein NMR spectroscopy is directly sensitive to Mg(II) binding to the
enzyme, Mn(II) competes with Mg(II) for common sites(s) on PvuII endonuclease. Substitution of the conserved active site carboxylate Glu68 with Ala resulted in a loss of affinity for both
equivalents of both Ca(II) and Mn(II). Interestingly, the active site mutant D58A retained an affinity for Mn(II) with K
d
≈ 2 mM. Mn(II) paramagnetic broadening in 19F spectra of wild-type and mutant 3-fluorotyrosine PvuII endonucleases are consistent with ITC results. Chemical shift analysis of 3-fluorotyrosine mutant enzymes is consistent
with a perturbed conformation for D58A. Therefore, free PvuII endonuclease binds metal ions, and metal ion binding can precede DNA binding. Further, while Glu68 is critical to metal
ion binding, Asp58 does not appear to be critical to the binding of at least one metal ion and appears to also have a role
in structure. These findings provide impetus for exploring the roles of multiple metal ions in the structure and function
of this representative endonuclease.
Received: 30 March 1999 / Accepted: 28 September 1999 相似文献
7.
The interactions of lysozyme with caffeine (Caf), theophylline (Tph) and theobromine (Tbr) were investigated using UV–Vis
absorption, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques. The results revealed
that Caf (Tph or Tbr) caused the fluorescence quenching of lysozyme by the formation of Caf (Tph or Tbr)–lysozyme complex.
The binding constants (K
A) and thermodynamic parameters (ΔG°, ΔH°, ΔS°) at two different temperatures, the binding locality, and the binding power were obtained. The results showed that the process
of binding Caf (Tph or Tbr) to lysozyme was a spontaneous molecular interaction procedure and the hydrophobic and electrostatic
interactions play a major role in stabilizing the complex; The distance r between donor (lysozyme) and acceptor (Caf, Tph or Tbr) was obtained according to fluorescence resonance energy transfer.
The effect of Caf (Tph or Tbr) on the conformation of lysozyme was analyzed using synchronous fluorescence and three-dimensional
fluorescence spectra techniques. The results showed that the binding of Caf (Tph or Tbr) to lysozyme induced some micro-environmental
and conformational changes in lysozyme and disturbed the environment of the polypeptide of lysozyme. 相似文献
8.
Zanaty R. Komy Rabei M. Gabar Ahmed A. Shoriet Rehab M. Mohammed 《World journal of microbiology & biotechnology》2006,22(9):975-982
Summary The ability of Pseudomonas
aeruginosa to accumulate Cd(II) ions from wastewater industries was experimentally investigated and mathematically modelled. From the potentiometric titration and non-ideal competitive analysis (NICA) model, it was found that the biomass contains three acidic sites. The values of proton binding (pK
i
=1.66±3.26×10−3, 1.92±1.63×10−4 and 2.16±3.79×10−4) and binding constant of cadmium metal ions (pK
M1=1.99±2.45×10−3 and pK
M2=1.67±4.08×10−3) on the whole surface of biomass showed that protonated functional groups and biosorption of Cd(II) ions could be attributed to a monodentate binding to one acidic site, mainly the carboxylic group. From the isothermal sorption experimental data and Langmuir model, it was also found that the value of Langmuir equilibrium (pK
f) constant is 2.04±2.1×10−5 suggesting that the carboxyl group is the main active binding site. In addition, results showed that the maximum cadmium capacity (q
max) and affinity of biomass towards cadmium metal ions (b) at pH 5.1 and 20 min were 96.5±0.06 mg/g and 3.40×10−3± 2.10×10−3, respectively. Finally, interfering metal ions such as Pb(II), Cu(II), Cr(III), Zn(II), Fe(II), Mn(II), Ca(II) and Mg(II) inhibited Cd(II) uptake. Comparing the biosorption of Cd(II) by various Pseudomonas isolates from contaminated environment samples (soil and sewage treatment plant) showed that maximum capacities and equilibrium times were different, indicating that there was a discrepancy in the chemical composition between biomasses of different strains. 相似文献
9.
The binding of [Dy(dmp)2Cl3(OH2)], where dmp is 2,9-dimethyl 1,10-phenanthroline, with Fish salmon DNA (FS-DNA) is investigated by absorption and emission spectroscopy, quenching studies, salt dependent, and gel electrophoresis. The binding constant (Kb) of the interaction is calculated as (1.27 ± .05) × 105 M?1 from absorption spectral titration data. The Stern–Volmer constant (KSV), thermodynamic parameters involves ΔG°, ?H°, and ?S° are calculated by fluorescent data and Van’t Hoff equation. The thermodynamic studies show that the reaction for the binding of the complex with FS-DNA is endothermic and entropically driven (ΔS° > 0, ΔH° > 0). The effect of the complex concentration on FS-DNA cleavage reactions is also investigated by gel electrophoresis. Furthermore, the Dy(III) complex has been screened for its antibacterial activity. The experimental results suggest that the Dy(III) complex binds significantly to FS-DNA by hydrophobic groove binding mode and the complex has more efficient antibacterial activity compared to its metal salt. 相似文献
10.
O. I. Smotrov V. M. Borzenkov V. I. Surovtsev 《Russian Journal of Bioorganic Chemistry》2011,37(5):564-568
The influence of pH within the range 6.9–10.0 on the kinetic parameters of Micrococcus lysodeicticus cell lysis catalyzed by hen egg lysozyme has been studied at 25°C and 37°C. The effective pK
b values have been calculated for the group determining lysozyme catalytic activity. The ΔH
ion value indicates that this group is a carboxyl, although its pK (9.15 at 25°C) is far beyond the range characteristic of carboxylic groups. The cause of this abnormal pK
b value is supposed to be the strong negative charge of the bacterial cell wall. As a result, the enzyme, which catalyzes the
hydrolysis of N-acetylglucosamine-N-acetylmuramic acid copolymer, operates in a highly acidic microenvironment. 相似文献
11.
Bruylants G Wintjens R Looze Y Redfield C Bartik K 《European biophysics journal : EBJ》2007,37(1):11-18
Protonation/deprotonation equilibria are frequently linked to binding processes involving proteins. The presence of these
thermodynamically linked equilibria affects the observable thermodynamic parameters of the interaction (K
obs, ΔH
obs0). In order to try and elucidate the energetic factors that govern these binding processes, a complete thermodynamic characterisation
of each intrinsic equilibrium linked to the complexation event is needed and should furthermore be correlated to structural
information. We present here a detailed study, using NMR and ITC, of the interaction between α-chymotrypsin and one of its
competitive inhibitors, proflavin. By performing proflavin titrations of the enzyme, at different pH values, we were able
to highlight by NMR the effect of the complexation of the inhibitor on the ionisable residues of the catalytic triad of the
enzyme. Using ITC we determined the intrinsic thermodynamic parameters of the different equilibria linked to the binding process.
The possible driving forces of the interaction between α-chymotrypsin and proflavin are discussed in the light of the experimental
data and on the basis of a model of the complex. This study emphasises the complementarities between ITC and NMR for the study
of binding processes involving protonation/deprotonation equilibria.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-8):1711-1714
Abstract Measurements of interaction of 7-methyl-GTP eIF4E from S. cerevisiae were performed by means of two methods: Isothermal Titration Calorimetry (ITC) and fluorescence titration. The equilibrium association constants (Kas) derived from the two methods show significantly different affinity of yeast eIF4E for the mRNA 5′ cap than those of the murine and human proteins. The observed differences in the Kas values and the enthalpy changes of the association (ΔH°) suggest some dissimilarity in the mode of binding and stabilization of cap in the complexes with eIF4E from various sources. 相似文献
13.
14.
S. Yu. Rakhmetova S. P. Radko O. V. Gnedenko N. V. Bodoev A. S. Ivanov A. I. Archakov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2011,5(2):139-143
Aptamers interacting selectively with the anion-binding exosites 1 and 2 of thrombin were merged into dimeric oligonucleotide
constructs by means of a poly-(dT)-linker of 35 nucleotides (nt) in length. Complexes of thrombin with the aptamers and their
hetero- and homodimeric constructs were measured using an optical biosensor Biacore-3000. The K
D values obtained for the hetero- and homodimeric constructs were correspondingly 25–30- and 2–3-fold lower than those for
the primary aptamers. Analysis of temperature dependencies of the K
D values within the temperature interval of 10–40°C has shown that affinity increases with the temperature decrease. The values
of the enthalpy change ΔH upon formation of complexes of thrombin with the aptamers and the heterodimeric construct were basically the same. The value
of the entropy change ΔS upon complex formation of thrombin with the aptamer heterodimeric construct was 1.5–2-fold higher than the ΔS values for the complexes with the aptamers. The complex formation and dissociation rates increased with the elevation of
temperature from 10 to 37°C. However, at both temperatures the dissociation rate for the complex of thrombin with the heterodimeric
construct was evidently lower that for the complexes with the aptamers. 相似文献
15.
Kasieczka-Burnecka M Kuc K Kalinowska H Knap M Turkiewicz M 《Applied microbiology and biotechnology》2007,77(1):77-89
Two extracellular tannin acyl hydrolases (TAH I and TAH II) produced by an Antarctic filamentous fungus Verticillium sp. P9 were purified to homogeneity (7.9- and 10.5-fold with a yield of 1.6 and 0.9%, respectively) and characterized. TAH
I and TAH II are multimeric (each consisting of approximately 40 and 46 kDa sub-units) glycoproteins containing 11 and 26%
carbohydrates, respectively, and their molecular mass is approximately 155 kDa. TAH I and TAH II are optimally active at pH
of 5.5 and 25 and 20°C, respectively. Both the enzymes were activated by Mg2+and Br− ions and 0.5–2.0 M urea and inhibited by other metal ions (Zn2+, Cu2+, K+, Cd2+, Ag+, Fe3+, Mn2+, Co2+, Hg2+, Pb2+ and Sn2+), anions, Tween 20, Tween 60, Tween 80, Triton X-100, sodium dodecyl sulphate, β-mercaptoethanol, α-glutathione and 4-chloromercuribenzoate.
Both tannases more efficiently hydrolyzed tannic acid than methyl gallate. E
a of these reactions and temperature dependence (at 0–30°C) of k
cat, k
cat/K
m, ΔG*, ΔH* and ΔS* for both the enzymes and substrates were determined. The k
cat and k
cat/K
m values (for both the substrates) were considerably higher for the combined preparation of TAH I and TAH II. 相似文献
16.
S. Aime Mauro Botta Mauro Fasano Simonetta Geninatti Crich Enzo Terreno 《Journal of biological inorganic chemistry》1996,1(4):312-319
The non-covalent interaction between human serum albumin (HSA) and DOTA-like Gd(III) complexes containing hydrophobic benzyloxymethyl
(BOM) substituents has been thoroughly investigated by measuring the solvent proton relaxation rates of their aqueous solutions.
The binding association constants (K
A) to HSA are directly related to the number of hydrophobic substituents present on the surface of the complexes. Furthermore,
an estimation of ΔH° and ΔS° has been obtained by the temperature dependence of K
A. Assays performed with the competitor probes warfarin and ibuprofen established that the complexes interact with HSA through
two nearly equivalent binding sites located in the subdomains IIA and IIIA of the protein. Strong relaxation enhancements,
promoted by the formation of slowly tumbling paramagnetic adducts, have been measured at 20 MHz for complexes containing two
and three hydrophobic substituents. The macromolecular adduct with the latter species has a relaxivity of 53.2±0.7 mM–1 s–1, which represents the highest value so far reported for a Gd(III) complex. The temperature dependence of the relaxivity for
the paramagnetic adducts with HSA indicates long exchange lifetimes for the water molecules dipolarly interacting with the
paramagnetic centre. This is likely to be related to the formation, upon hydrophobic interaction of the complexes with HSA,
of a clathrate-like, second-coordination-sphere arrangement of water molecules. Besides affecting the dissociative pathway
of the coordinated water molecule, this water arrangement may itself significantly contribute to enhancement of the bulk solvent
relaxation rate.
Received: 6 November 1995 / Accepted: 17 April 1996 相似文献
17.
Binding of ethidium to bacteriophage T7 and T7 deletion mutants 总被引:1,自引:0,他引:1
Equilibrium binding of ethidium, quantitated by fluorescence enhancement, to DNA packaged in bacteriophage T7 and T7 deletion mutants has been compared with the binding of this dye to DNA released from its capsid (free DNA). During achievement of apparent equilibrium binding, no change in bacteriophage T7 structure occurred, by the criterion of agarose gel electrophoresis. However, excessive incubation with ethidium bromide caused detectable changes in bacteriophage structure, a possible explanation of disagreements in similar studies previously performed with T-even bacteriophages. Scatchard plots for packaged DNA had a curvature greater than the previously demonstrated [Bresloff, J. L. & Crothers, D. M. (1981) Biochemistry 20 , 3547–3553] curvature for free DNA. By treating plots for packaged DNA as though they were biphasic, it was found that binding to most sites occurred with an apparent association constant (Kap) 3.3–4.3 times lower than the Kap of free DNA. The number of these sites increased significantly as the density of packaged DNA was decreased by use of the deletion mutants. Values of ΔH° for these sites were negative and equal to the ΔH° for free DNA; values of ΔS° were positive and about half the ΔS° for free DNA. A second class of sites, roughly 1.2% of the total, had a significantly higher Kap and more negative ΔH° than those of the majority of sites. 相似文献
18.
Atmanand M. Bagoji Jayant I. Gowda Naveen M. Gokavi 《Journal of biomolecular structure & dynamics》2017,35(11):2395-2406
The interaction between thiamine hydrochloride (TA) and bovine serum albumin (BSA) was investigated by fluorescence, FTIR, UV–vis spectroscopic and cyclic voltammetric techniques under optimised physiological condition. The fluorescence intensity of BSA is gradually decreased upon addition of TA due to the formation of a BSA–TA complex. The binding parameters were evaluated and their behaviour at different temperatures was analysed. The quenching constants (Ksv) obtained were 2.6 × 104, 2.2 × 104 and 2.0 × 104 L mol?1 at 288, 298 and 308 K, respectively. The binding mechanism was static-type quenching. The values of ΔH° and ΔS° were found to be 26.87 kJ mol?1 and 21.3 J K?1 mol?1, and indicated that electrostatic interaction was the principal intermolecular force. The changes in the secondary structure of BSA upon interaction with TA were confirmed by synchronous and 3-D spectral results. Site probe studies reveal that TA is located in site I of BSA. The effects of some common metal ions on binding of BSA–TA complex were also investigated. 相似文献
19.
《Biocatalysis and Biotransformation》2013,31(4):217-225
AbstractThe gene encoding CtCBM6B of Clostridium thermocellum α-L-arabinofuranosidase (Ct43Araf) was cloned in pET-21a(+) vector, over-expressed using Escherichia coli BL-21(DE3) cells and purified by immobilized metal-ion affinity chromatography (IMAC). The recombinant CtCBM6B showed a molecular size close to 15 kDa by SDS-PAGE analysis, which was close to the expected size of 14.74 kDa. The ligand-binding affinity of CtCBM6B was assessed against ligands for which the catalytic enzyme, Ct43Araf showed maximum activity. The affinity-gel electrophoresis of CtCBM6B with rye arabinoxylan showed lower equilibrium association constant (Ka, 4.0% C? 1), whereas, it exhibited higher affinity (Ka, 19.6% C? 1) with oat spelt xylan. The ligand-binding analysis of CtCBM6B by fluorescence spectroscopy also revealed similar results with low Ka (3.26% C? 1) with rye arabinoxylan and higher affinity for oat spelt xylan (Ka, 17.9% C? 1) which was corroborated by greater blue-shift in case of oat spelt xylan binding. The CtCBM6B binding with insoluble wheat arabinoxylan by adsorption isotherm analysis showed significant binding affinity as reflected by the equilibrium association constant (Ka), 9.4 × 103 M? 1. The qualitative analysis by SDS-PAGE also corroborated the CtCBM6B binding with insoluble wheat arabinoxylan. The protein-melting curve of CtCBM6B displayed the peak shift from 53°C to 59°C in the presence of Ca2+ ions indicating that Ca2+ ions impart thermal stability to the CtCBM6B structure. 相似文献
20.
Studies on the synthesis,characterization, human serum albumin binding and biological activity of single chain surfactant–cobalt(III) complexes
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G. Vignesh K. Sugumar S. Arunachalam S. Vignesh R. Arthur James R. Arun K. Premkumar 《Luminescence》2016,31(2):523-532
The interaction of surfactant–cobalt(III) complexes [Co(bpy)(dien)TA](ClO4)3 · 3H2O (1) and [Co(dien)(phen)TA](ClO4)3 · 4H2O (2), where bpy = 2,2′‐bipyridine, dien = diethylenetriamine, phen = 1,10‐phenanthroline and TA = tetradecylamine with human serum albumin (HSA) under physiological conditions was analyzed using steady state, synchronous, 3D fluorescence, UV/visabsorption and circular dichroism spectroscopic techniques. The results show that these complexes cause the fluorescence quenching of HSA through a static mechanism. The binding constant (Kb) and number of binding‐sites (n) were obtained at different temperatures. The corresponding thermodynamic parameters (?G°, ?H° and ?S°) and Ea were also obtained. According to Förster's non‐radiation energy transfer theory, the binding distance (r) between the complexes and HSA were calculated. The results of synchronous and 3D fluorescence spectroscopy indicate that the binding process has changed considerably the polarity around the fluorophores, along with changes in the conformation of the protein. The antimicrobial and anticancer activities of the complexes were tested and the results show that the complexes have good activities against pathogenic microorganisms and cancer cells. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献