BSA Fluorescence Research Articles

Multi-spectral and docking assessments to explore the combination of an antiviral drug, entecavir with bovine serum albumin

Molecular interaction of entecavir (ETV) with the transport protein, albumin from bovine serum (BSA) was explored through multispectral and molecular docking approaches. The BSA fluorescence was appreciably quenched upon ETV binding and the quenching nature was static. The ETV–BSA complexation and the static quenching process were further reiterated using UV–visible absorption spectra. The binding constant (Ka) values of the complex were found as 1.47 × 104–4.0 × 103 M−1, which depicting a modarate binding strength in the ETV–BSA complexation. The experimental outcomes verified that the stable complexation was primarily influenced by hydrophobic interactions, hydrogen bonds and van der Waals forces. Synchronous and 3-D fluorescence spectral results demonstrated that ETV had significant impact on the hydrophobicity and polarity of the molecular environment near Tyr and Trp residues. Competitive site-markers displacement (with warfarin and ketoprofen) results discovered the suitable binding locus of ETV at site I in BSA. The molecular docking assessments also revealed that ETV formed hydrogen bonds and hydrophobic interactions with BSA, predominantly binding to site I (sub-domain IIA) of BSA.

Exploring the effect of surfactants on the interactions of manganese dioxide nanoparticles with biomolecules

Interactions of manganese dioxide nanoparticles (MnO2 NPs) with vital biomolecules namely deoxyribonucleic acid (DNA) and serum albumin (BSA) have been studied in association with different surfactants by using fluorescence (steady state, synchronous and 3D), UV-visible, resonance light scattering (RLS), dynamic light scattering (DLS), and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The esterase activity of serum albumin was tested in associations with MnO2 NPs and surfactants. The antioxidant potential of prepared NPs was also evaluated (DPPH method). Gel electrophoresis was carried out to analyze the effect of MnO2 NPs and surfactants on DNA. Presence of CTAB, Tween 20, DTAB and Tween 80 enhanced nanoparticle-protein binding. Tween 20 based nanoparticle systems showed long-term stability and biocompatibility. The quenching of BSA fluorescence emission in presence of MnO2 NPs alone and along with Tween 20 revealed stronger association of nanoparticles with proteins. Enhancement in the esterase activity (BSA) was observed in the presence of Tween 20. Furthermore, radical scavenging activity showed highest antioxidant potential in presence of Tween 20. The enthalpy and entropy assessment for protein-NPs association showed the predominance of Vander Waals interactions and hydrogen bonding. The synchronous fluorescence analysis highlighted the involvement of tryptophan (Trp) in the MnO2 NPs-protein interactions. The study evaluates the influence of surfactant on the associations of MnO2 NPs with the essential biomolecules. The findings can be crucially utilized in designing biocompatible MnO2 formulations for long term applications. Communicated by Ramaswamy H. Sarma

Enantioselective effect of chiral prothioconazole on the conformation of bovine serum albumin

As a typical chiral triazole fungicide, the enantioselective toxicity of prothioconazole to environmental organisms is of increasing concern. Herein, the binding mechanism of chiral PTCs to BSA was investigated by multi-spectral technique and molecular docking. Fluorescence titration and fluorescence lifetime experiments fully established that quenching BSA fluorescence by chiral PTCs is static quenching and could spontaneously bind to BSA. Hydrophobic interactions dominate the binding process of chiral PTCs to BSA. Differently, although both chiral PTCs and BSA have a primary binding site, the difference in chiral isomerism leads to a stronger binding ability of S-PTC than R-PTC. Both configurations of PTC can change the conformation of BSA and induce changes in the microenvironment around its amino acid residues, and the effect of S-PTC is more significant. Overall, S-PTC exhibited a more substantial effect on BSA structure relative to R-PTC. That is, S-PTC may lead to more potent potential toxicological effects on environmental organisms. This study provides a comprehensive assessment of the environmental behavior of chiral pesticides and their potential toxicity to environmental organisms at the molecular level and provides a theoretical basis for the screening of highly effective and biologically less toxic enantiomers of chiral pesticides.

Ternary Cobalt (II)-Metformin-Glycine/Histidine/Proline Complexes: Multispectroscopic DNA, HSA, and BSA Interaction and Cytotoxicity Studies.

The synthesized water-soluble ternary complexes [Co(met)(gly)(Cl)2] (1), [Co(met)(hist)(Cl)2] (2), and [Co(met)(pro)(Cl)2] (3), (met = metformin, gly = glycine, hist = histidine, and pro = proline) were evaluated using spectro-analytical techniques, and the stereochemistry of the complexes was determined to be octahedral. UV-Vis absorption, competitive DNA-binding experiments using ethidium bromide (EB) by fluorescence, fluorescence emission studies, viscosity studies, and gel electrophoresis techniques were all employed to explore the binding characteristics of the cobalt (II) complexes with CT-DNA and groove-binding mechanism established. The salt-dependent association of the complexes to CT-DNA was investigated using UV-Vis spectrophotometric analysis. The association of the cobalt (II) complexes with BSA and HSA was explored by utilizing UV-Vis absorption and fluorescence spectroscopy approaches. The findings show that the complexes exhibit adequate capacity to quench BSA and HSA fluorescence and that the binding response is mostly a static quenching mechanism. The cytotoxicity of the complexes has also been appraised with the human breast adenocarcinoma cell lines (MCF-7) and (MDA-MB-231) by utilizing the MTT assay. For each cell line, the IC50 values were computed. In both cell lines, all the complexes were active.

Analysis of the level of oxidative stress by assessing the damage to the plasma protein serum albumin under the influence of an oxidizing agent

Oxidative stress, which leads to oxidative modification of various macromolecules, including proteins, is now considered an important pathogenetic link in many diseases. In this work, oxidative damage to a blood plasma protein, bovine serum albumin BSA, under the action of an oxidizing agent, hydrogen peroxide H2O2, was studied by spectrofluorometric method. The H2O2 concentration-dependent quenching of the intrinsic fluorescence of BSA is shown. BSA fluorescence quenching constants in hydrogen peroxide solutions are calculated by mathematical modeling methods. The dependences found in the fluorescence quenching constants are explained both by oxidative damage to the microenvironment of BSA tryptophan residues and by changes in the native conformation of protein globules upon oxidative damage. More significant peroxide damage to BSA occurs at lower pH values due to the fact that H2O2, as an oxidizing agent, acts more strongly in an acidic environment. The registered quenching of the protein's own fluorescence when damaged by an oxidizing agent can be used as a medical method for assessing the level of oxidative stress in the body in the diagnosis of a number of diseases.

FLUORESCENCE STUDIES ON THE BLOOD PLASMA ALBUMIN INTERACTION WITH 4-HYDROXY-2-METHYLQUINOLINE

Blood plasma albumin (bovine serum albumin, BSA) interaction with a biologically active reagent 4-hydroxy-2-methylquinoline (4H2MQ) has been studied using fluorescence spectroscopy methods (steady state, synchronous, excitation/emission matrix, 3D spectra). With the addition of 4H2MQ, no changes in the spectral characteristics of BSA (fluorescence emission intensity and λmax position) are observed; only the symmetry of the BSA emission spectrum is changed and the full width at half maximum is decreased. The analysis of synchronous and 3D fluorescence spectra showed the existence of three emitting species in this system, which could be a result of changes in the fluorescence and photochemical properties of 4H2MQ.

The different interactions of two anticancer drugs with bovine serum albumin based on multi-spectrum method combined with molecular dynamics simulations

Paclitaxel is the best natural anticancer drug and artemisinin also has anticancer effect. In this study, the interactions between BSA and these two drugs were determined in PBS (pH 7.40) by multi-spectroscopic method and molecular dynamics (MD) simulations. The results showed that paclitaxel and artemisinin could statically quench the BSA fluorescence when the complexes were formed and the stoichiometric ratio of BSA-drugs was 1:1. Particularly, the BSA-paclitaxel complex was more stable than BSA-artemisinin complex. During the binding, the surroundings around Trp residue site was largely affected than Tyr site, especially Trp 214 to a more hydrophobic environment. In addition, the binding processes were mainly spontaneous through electrostatic force interaction. In summary, we concluded that the free drug of paclitaxel in blood was low and duration time of artemisinin was shorter.

Exploring the fluorescence quenching interaction of amino acids and protein with natural organic matter by a multi-spectroscopic method

AbstractThe main objective of this research was to explore the fluorescence quenching mechanism of a humic substance (Suwannee River natural organic matter (SWNOM)) to amino acids (tryptophan, tyrosine) and protein (bovine serum albumin, (BSA)) by multi-spectroscopic methods. The locations of the peaks of tryptophan, tyrosine, and BSA from Parallel Factor Analysis were at Ex/Em 280/356 nm, 275/302 nm, and 280/344 nm, respectively. For SWNOM, two peaks appeared at Ex/Em of 240/448 nm, and 350/450 nm. Static quenching was the dominant quenching mechanism between BSA and SWNOM, whereas no quenching was observed between tryptophan or tyrosine and SWNOM. Fourier-transform infrared spectroscopy and thermodynamic calculation demonstrated that hydrogen bonding and van der Waals force are the potential binding forces of the BSA-SWNOM complex, as a result of rearrangement in the secondary polypeptide carbonyl hydrogen bonding network of BSA. This rearrangement led to the conformational change in BSA that induced quenching of BSA fluorescence by SWNOM.

Thermodynamic analysis of albumin interaction with monosodium glutamate food additive: Insights from multi-spectroscopic and molecular docking approaches

Monosodium glutamate (MSG) is an example of food additive, which is used as a flavor enhancer in various foodstuffs. Because of its extensive use in food production, the toxicology and possible negative effects of MSG additive on albumin must be well investigated. Therefore, for the first time, the binding of BSA and MSG have been studied using multispectroscopic and molecular modeling approaches under physiological conditions. BSA fluorescence intensity has been diminished upon the addition of increased MSG concentrations. The Stern–Volmer quenching constant (KSV) value increase with rising temperature and bimolecular quenching rate constant of protein (kq) value was larger than 2.0 × 1010 L mol− 1 s− 1, which shows that the fluorescence quenching was both dynamic and static due to the BSA-MSG complex formation. The positive values for both ΔS0 (888.291 J mol−1K−1) and ΔH0 (243.903 kJ mol−1) proposed that the hydrophobic forces played predominant roles in the binding of MSG to BSA. Also, the negative value of ΔG0 indicated that the interaction between two compounds is spontaneous and enthalpy driven. The UV–VIS spectra results confirmed the binding of MSG to BSA. The circular dichroism analysis exhibited that BSA conformation change occur upon interaction with MSG. Moreover, molecular modeling analysis indicated that glutamate remarkably tends to bind into a cavity above Sudlow II with lowest calculated binding energy of - 8.24 kcal/mol.

Spectroscopic evaluation of Zn (II) complexes with drug analogues: Interactions with BSA and the pH effect on the drug-Zn (II) system.

Using UV-Vis, FT-IR, fluorescence spectroscopy and protein-ligand docking, the interactions between the zinc complexes with drug analogues and bovine serum albumin were investigated. In addition, considering the ubiquitous presence of zinc ions in the human system, we studied the interactions between this ion with hymecromone, dihydropyridine analogue, and acetamide, as well as the pH influence on these systems. The complexes were synthesized by interaction between the ligands and the Zn (II) ion in a 2:1M ratio. Elemental analysis, FT-IR, and UV-Vis spectroscopy studies investigated the structure of the synthesized complexes. Fluorescence spectroscopy, UV-Vis, molecular docking and molecular dynamics were used to study the interactions of the Zn complexes with the BSA. The drug-Zn (II) system's pH effect was investigated using UV-Vis spectroscopy. After the complexation with the zinc, the drug molecules exhibited higher apparent binding affinity to BSA. BSA's fluorescence efficiency by the drug analogues was enhanced. In addition, molecular modelling was used to classify the residue of amino acids in the BSA playing key roles in this binding interaction. An increase in pH appears to contribute to alkaline hydrolysis of the Zn (II) molecules.

Exploring the binding interaction between bovine serum albumin and perindopril as well as influence of metal ions using multi-spectroscopic, molecular docking and DFT calculation

The binding characteristics of BSA with perindopril, a third-generation angiotensin-converting enzyme inhibitor, was investigated using various spectroscopic approaches combined with molecular simulation including molecular docking and density functional theory calculation. Meantime, the influence of some trace metal ions on the binding characteristics of BSA with perindopril was investigated. The findings indicated the perindopril quenched BSA fluorescence in a static way. The values of binding site (n) and binding constant (Kb) of perindopril on BSA were close to 1 and 8.12 × 103 M−1 at 298 K, respectively, indicating that the binding affinity was moderate and the stoichiometric ratio of the perindopril-BSA complex was 1:1. Thermodynamic analysis results revealed that the ΔG0, ΔH0, and ΔS0 values were negative, demonstrating the binding interaction was a spontaneous and exothermic process, the interaction forces were mainly hydrogen bonds and van der Waals forces. The results of the replacement experiments and molecular simulations indicated that perindopril bound to the groove between sub-domain IIB and IIA. Furthermore, the results also revealed the BSA conformation altered slightly during binding with perindopril and the existence of transition metal ions would result in the increase in the Kb value of perindopril on BSA, resulting in the decline in the concentration of free perindopril. The frontier molecular orbitals and other quantum chemical parameters as well as conformation of perindopril in BSA complex obviously altered for forming the more stable perindopril-BSA complex.

Synthesis, photophysical behavior and biomolecular reactivity of new triphenylphosphonium-based Pd(II)salphens as new anticancer candidates

The synthesis of new bis-triphenylphosphonium-based dimethlysalphens (salphen = N,N`-bis-(salicylidene)-o-phenylenediimine) and their complexes (Pd(II)-salphens) for chemotherapeutic applications were reported. The in vitro anticancer efficacy of new compounds against human hepatocellular carcinoma (HepG2) cell lines demonstrated higher activity for Pd-complexes as compared with their parent ligands. Among tested compounds, Pd(II)-salphen3 was found to be the most potent one in the suppression of HepG2 proliferation (IC50 = 3.01 μM), ˜3-fold lower than the clinical drug (cisplatin, CDDP) (IC50 = 8.28 μM). The Pd(II)-salphens can effectively bind to CT-DNA via a non-covalent interaction (intercalation/ electrostatic) as revealed from the hyperchromism of 28–53% along with 3–6 nm bathochromism observed during the electronic absorption titration of Pd(II)-salphens with CT-DNA. On the other hand, the H-bonding and hydrophobic interactions play crucial roles in the binding of Pd(II)-salphens to BSA as indicating from the BSA fluorescence quenching by Pd(II) complexes. Noteworthy, Pd(II)-salphen3 displayed the highest reactivity towards DNA/ BSA with intrinsic binding constants (Kb/ KF) (3.01 × 105/ 2.95 × 106 M–1).

Binding of l-tryptophan and bovine serum albumin by novel gold nanoparticles capped with amphiphilic sulfonatomethylated calixresorcinarenes

A simple, one-step synthesis of spherical gold nanoparticles (dcore=38 and 25nm) in aqueous solution has been carried out using sulfonatomethylated calixresorcinarenes with methyl (C1S) and pentyl (C5S) substituents on the lower rim both as reducing and stabilizing agents. The nanoparticles obtained, Au@C1S and Au@C5S, were characterized by absorption spectrophotometry, TEM, DLS, IR and TGA. The gold nanoparticles are stabilized by the interaction that occurs between macrocycles' sulfo-groups and the metal surface. It has been shown, that Au@C5S nanoparticles have a higher thermal stability than Au@C1S nanoparticles due to the denser packing of the macrocycle on the surface of gold nanoparticles caused by amphiphilic nature of the C5S macrocycle. C5S or Au@C5S associate cooperatively with l-tryptophan to form a nanoscale system capable of a spectral response to changing pH in aqueous solution.A detailed study of the interaction of С5S and Au@C5S with BSA in aqueous solution was carried out by spectrophotometry, DLS and fluorimetry. It was found that C5S and Au@C5S both form stable complexes with the protein, which was confirmed by the static character of the quenching of BSA fluorescence. The mechanism of the interaction of BSA with the macrocycles in aqueous solution and on the surface of gold nanoparticles was investigated. The quenching (KSV) and binding (Kas) constants, the number of binding sites (n), and thermodynamic interaction parameters (ΔG, ΔH, ΔS) were calculated. It was found that the process of protein binding by the free macrocycle and the modified gold nanoparticles is exothermic and spontaneous, and hydrogen bonding and van der Waals interactions make a major contribution into the binding. The synchronous fluorescence method showed that the binding of BSA with macrocycle influences the microenvironment of the tryptophan residues in protein molecule. The interaction of С5S and Au@C5S with BSA leads to the changes in the protein structure as well as in the physicochemical characteristics of gold nanoparticles, which is a promising aspect in the use of such systems for transport of protein molecules or their visualization-detection in biological media.

Photo Relaxation Change and Emission Quenching in Different Sizes of PbS‐Nanoparticles‐Protein Corona

AbstractIn this study, energy transfer from BSA to different size semiconductor nanoparticles PbS was analyzed by using photo Relaxation change and emission quenching analysis. Structures of thePbS NPs are studied by XRD, TEM, and FT‐IR measurements. The band gap and crystal size of PbS suggest the quantum confinement effect. Photo current of the BSA‐PbS NPs bioconjugate system increased compared to bare PbS nanoparticles from nA to μA. Change in photo relaxation life time of the bare PbS NP and PbS NPs‐BSA bioconjugate system is particle size dependent and interaction dependent. PbS NPs‐BSA bioconjugate were characterized by steady‐state fluorescence spectroscopy to determine the magnitude and mechanism of the energy transfer. It was found that the BSA fluorescence was quenched after the addition of PbS nanoparticles. Quenching of protein is large for larger size PbS nanoparticles. DLS study confirmed that BSA was adsorbed onto the surface of nanoparticles, creating a favourable geometry for quenching. Aggregation of BSA around a single PbS nanoparticle is size dependent. Larger nanoparticles are responsible for hard as well as soft corona due to interaction.Our results, which include photo relaxation times, energy transfer efficiencies showed that energy transferred take place via the Fluorescence Resonance Energy Transfer (FRET) mechanism. These energy transfer processes between protein molecules and PbS nanoparticles, will depend on the size of the particles involved.

Effects of fetal calf serum on cGMP pathway and oocyte lipid metabolism in vitro.

Intracellular levels of cyclic nucleotides, such as cGMP, are involved in the regulation of adipocyte lipolysis. Cumulus-oocyte complexes (COCs) express enzymes that both synthesise (guanylate cyclase) and degrade (phosphodiesterase (PDE) 5A) cGMP. Because serum interferes with lipid metabolism, its effects on the cGMP pathway and lipid content in bovine COCs were examined. COCs were matured in medium containing fetal calf serum (FCS; 2% or 10%) or 0.4% bovine serum albumin (BSA; control). At both 2% and 10%, FCS decreased cGMP levels in COCs compared with BSA (0.64 and 1.04 vs 9.46 fmol per COC respectively; P<0.05) and decreased transcript levels of guanylate cyclase 1, soluble, beta 3 (GUCY1B3), whereas PDE5A levels were increased. FCS also affected the expression of genes related to lipolysis, increasing relative expression of perilipin 2 (PLIN2) and carnitine palmitoyltransferase 1B (CPT1B) in cumulus cells. Effects of FCS and cGMP on the lipid content of oocytes and embryos were evaluated by Nile red staining. COCs were matured with 10% FCS, FCS+10-5 M sildenafil (SDF), a PDE5 inhibitor, or 0.4% BSA. The lipid content was increased in oocytes matured in FCS compared with BSA (fluorescence intensity 20.1 vs 17.61 respectively; P<0.05), whereas the lipid content in oocytes matured in FCS+SDF (fluorescence intensity 16.33) was similar to that in the BSA-treated group (P>0.05). In addition, lipid content was higher in embryos from oocytes matured with FCS than BSA (fluorescence intensity 31.12 vs 22.31 respectively; P<0.05), but was increased even further in the FCS+SDF-treated group (fluorescence intensity 40.35; P<0.05), possibly due to a compensatory mechanism during embryo culture without SDF for the reduction in lipid content during IVM. The present study provides, for the first time, evidence that the cGMP pathway may be involved in lipid metabolism in bovine COCs and that this pathway is affected by FCS.

Microwave-assisted green synthesis of some nanoconjugated copolymers: characterisation and fluorescence quenching studies with bovine serum albumin

The copolymer POPD-co-PNA quenches BSA fluorescence revealing many of its photophysical characteristics including a higher association constant and its scintillating presence on the latter.

Salmonella Disrupts Host Endocytic Trafficking by SopD2-Mediated Inhibition of Rab7.

Intracellular bacterial pathogens of a diverse nature share the ability to evade host immunity by impairing trafficking of endocytic cargo to lysosomes for degradation, a process that is poorly understood. Here, we show that the Salmonella enterica type 3 secreted effector SopD2 mediates this process by binding the host regulatory GTPase Rab7 and inhibiting its nucleotide exchange. Consequently, this limits Rab7 interaction with its dynein- and kinesin-binding effectors RILP and FYCO1 and thereby disrupts host-driven regulation of microtubule motors. Our study identifies a bacterial effector capable of directly binding and thereby modulating Rab7 activity and a mechanism of endocytic trafficking disruption that may provide insight into the pathogenesis of other bacteria. Additionally, we provide a powerful tool for the study of Rab7 function, and a potential therapeutic target.

In vitro and in vivo antioxidant, cytotoxic, and anti-chronic inflammatory arthritic effect of selenium nanoparticles.

The toxicity of selenium (Se) as an antioxidant supplement in the treatment of arthritis is debatable. In this study, Dextrin stabilized Se nanoparticles (SeNP) of size 64 nm ± 0.158 were used to explore its effects as a potent antioxidant with reduced toxicity in both in vitro and in vivo. In vitro toxicity of SeNP was determined using cytotoxicity assay. In vitro interactions of SeNP with DNA and protein was established. Subacute toxicity of SeNP was studied. Wistar rats with complete freunds adjuvant induced arthritis were used. Various concentrations of SeNP per kg body weight were fed orally daily upto to 21 days. Arthritic profile based on paw swelling, histopathological changes in joints, blood indices, and antioxidant enzymes level in organs such as liver, kidney, and spleen were investigated. Dextrin-SeNP when interacted with NIH-3T3 cells showed 15% cytotoxicity at 100 µg/mL whereas, bulk Se showed 95% at the same concentration. SeNP at 250 µg/mL showed protective effect on DNA. Interaction of SeNP with BSA showed increase in quenching of BSA fluorescence. SeNP did not show any subacute toxicity at concentration as high as 5 mg/kg b.w. in Wistar rats. SeNP at a concentration of 250 µg/kg b.w. acted as potent anti-inflammatory agent and significantly reduced (p < 0.05) arthritis induced parameters. The enzymatic antioxidant levels in liver, kidney, and spleen were restored significantly (p < 0.05) at 500 µg/kg b.w. while CRP was regained to normal at concentration of 100 µg/kg b.w. concluding SeNP at 500 µg/kg b.w. can be a potential antiarthritic drug supplement. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 993-1003, 2016.

Synthesis, spectral characterization, crystal structure and in vitro DNA/protein binding studies of phosphorous ylide palladacyclic complexes containing azide group

The reaction between (4-nitrobenzoylmethylene)triphenylphosphorane Pd(II) complex [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}(μ-Cl)]2 and excess of NaN3 resulted in the μ-N3 bridged Pd(II) complex [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}(μ-N3)]2 (1), which underwent bridge cleavage reactions with monodentate ligands to afford the monomeric, neutral complexes [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}N3(L)] (L=Me3Py (1a), PPh3 (1b)). The complexes were identified and characterized by elemental analyses, infrared (IR), 1H, 13C{1H} and 31P{1H} NMR spectroscopy. The molecular structure of 1b was determined by single-crystal X-ray diffraction. The interactions of complexes with FS-DNA were investigated using UV absorption and fluorescence spectra. The results suggested that both complexes could interact with FS-DNA through the intercalation mode and follow the binding affinity order of 1a>1b. The reactivity toward protein BSA revealed that the quenching of BSA fluorescence by the two complexes are static quenching, and complex 1a exhibits a higher BSA-binding ability than the complex 1b.

Spectroscopic Investigation on the Interaction of Ferrocene Containing Hyperbranched Poly(amine) Ester with Model Plasma Protein

Mechanism of interaction between ferrocenyl-functionalized hyperbranched poly(amine) ester (HPAE-Fc) and model plasma protein-bovine serum albumin (BSA) was investigated using cyclicvoltammetry, differential pulsed voltammetry, fluorescence, UV–Vis absorption spectrometry and circular dichroism (CD). Some complicated interactions occurred between BSA and HPAE-Fc and the new redox centers appeared in the BSA/HPAE-Fc complex that changed and hindered the electron transfer of Fe/Fe2+. Stern–Volmer analysis of fluorescence quenching data showed that BSA fluorescence was statically quenched by HPAE-Fc, which implied that ground state complex formed between BSA and HPAE-Fc. The hydrogen bonds and vander Waals force play major roles in the reaction as indicated by the 1H NMR and variable temperature 1H NMR spectra and thermodynamic parameters. The distance, r between the donor (BSA) and acceptor (HPAE-Fc) was calculated based on the Forster’s theory of non-radiation energy transfer and was found to be 3.24 nm, which in turn indicated that HPAE-Fc can bind to BSA with high probability. Synchronous, three-dimensional fluorescence and CD studies indicated that the interaction of BSA with HPAE-Fc induced conformational changes in BSA with overall decrease in the α-helical structure and increase in β-pleated sheet structure. The molecular model of the interaction between HPAE-Fc and BSA was also presented according to the results in this study.