Subdomain IIA Of Bovine Serum Albumin Research Articles

Syntheses, structures, Hirshfeld surface analyses, BSA interactions and molecular docking studies of two leucine Schiff base complexes of oxovanadium(IV)

Two mixed-ligand oxovanadium(IV) complexes with a Schiff base derived from o-vanillin and leucine and 1,10-phenanthroline or 2,2´-bipyridine as a co-ligand, [VO(o-van-Leu)phen] (1) and [VO(o-van-Leu)bipy]·H2O (2), were prepared and structurally characterized by IR spectra, elemental analyses and single-crystal X-ray diffraction. The crystal structures reveal that each oxovanadium(IV) atom in complexes 1 and 2 is surrounded by a N3O3 coordination sphere to form a distorted octahedron with a Schiff base and neutral bidentate ligand phen or bipy. Hirshfeld surface analyses and 2D fingerprint plots indicated that the molecular packings in crystals were dominated by H···H, O···H/H···O, C···H/H···C and π-π interactions. The interactions of both complexes with bovine serum albumin (BSA) were studied by using various spectroscopic and molecular docking methods. BSA binding constants (K), estimated by UV–Vis spectroscopy, were 2.53 × 104M−1 for 1 and 3.18 × 104M−1 for 2, respectively. Together with results of fluorescence and CD spectral studies, it showed that complex 2 has a better affinity for BSA than complex 1. Molecular docking investigation indicated that the two complexes had the similar mode of binding and located within subdomain IIA of BSA. Complex 2 had greater binding activity with the binding free energy (∆Gbinding) of –6.5 kcal/mol than Complex 1 with ∆Gbinding of–5.42 kcal/mol, consisting with the analyses of spectroscopic experimental results.

Molecular interactions and binding dynamics of Alpelisib with serum albumins: insights from multi-spectroscopic techniques and molecular docking

Alpelisib (ALP) is a potent anti-cancer drug showing promising activity against advanced breast cancers. Hence, profound understanding of its binding dynamics within the physiological system is vital. Herein, we have investigated interaction of ALP with human serum albumin (HSA) and bovine serum albumin (BSA) using spectroscopic techniques like absorption, fluorescence, time-resolved, synchronous and 3D-fluorescence, FRET, FT-IR, CD, and molecular docking studies. The intrinsic fluorescence of both BSA and HSA quenched significantly by ALP with an appreciable red shift in its emission maxima. Stern-Volmer analysis showed increase in Ksv with temperature indicating involvement of dynamic quenching process. This was further validated by no significant change in absorption spectrum of BSA and HSA (at 280 nm) upon ALP interaction, and by results of fluorescence time-resolved lifetime studies. ALP exhibited moderately strong binding affinity with BSA (of the order 106 M−1) and HSA (of the order 105 M−1), and the major forces accountable for stabilizing the interactions are hydrophobic forces. Competitive drug binding experiments and molecular docking suggested that ALP binds to site I in subdomain IIA of BSA and HSA. The Förster distance r was found to be less than 8 nm and 0.5 Ro < r < 1.5 Ro which suggests possible energy transfer between donors BSA/HSA and acceptor ALP. Synchronous and 3D-fluoresecnce, FT-IR and CD studies indicated that ALP induces conformational changes of BSA and HSA upon interaction. Communicated by Ramaswamy H. Sarma

Insights into the interaction between the kusaginin and bovine serum albumin: Multi-spectroscopic techniques and computational approaches.

Kusaginin, as a phenylethanoid glycoside, which has exhibited wide antioxidant and antimicrobial properties. The molecular mechanism underlying the broad biological activities of kusaginin has not yet been well documented. In this paper, the interaction of kusaginin with bovine serum albumin (BSA) has been explored by fluorescence spectra, UV-vis absorption spectra, and circular dichroism (CD) spectra along with computational approaches. The fluorescence experiments showed that kusaginin could strongly quench the intrinsic fluorescence of BSA through both dynamic and static quenching mechanisms. The thermodynamic analysis suggested that hydrophobic force was the main force in stabilizing the BSA-kusaginin complex. In addition, conformation changes of BSA were observed from three-dimensional and synchronous fluorescence spectra, UV spectra, and CD spectra under experimental conditions. All these experimental results have been complemented and validated by the molecular docking and dynamic simulation studies, which revealed that kusaginin was bound on the hydrophobic cavity in subdomain IIA of BSA and formed a stable BSA-kusaginin complex. Finally, density functional theory (DFT) calculation further implied that hydrogen bonds also support stabilizing the BSA-kusaginin complex. This research may aid in understanding the pharmacological characteristics of kusaginin and provide a vital reference modeling for the design of analogues drugs.

Investigation on the interaction of brazilin with bovine serum albumin using multi-spectroscopic and computational methods: Exploring the binding mechanism and inhibitory effect on amyloid aggregation

Free and active concentration of drug in the blood plays a vital role in the disease treatment. Binding of drug to serum albumin, an important transport protein in plasma, usually improves its aqueous solubility, stability and bioactivity. Brazilin (Bra) is a natural compound extracted from Caesalpinia sappan with numerous pharmacological applications, while the behavior of Bra in circulatory system is still unknown. Therefore, in the present work, we firstly examined the interaction of Bra with bovine serum albumin (BSA) using various spectroscopic and computer simulation techniques. The static quenching mechanism and moderate binding affinity (2.18 × 104 M−1 at 298 K) were obtained through fluorescence spectroscopic measurement. Thermodynamic analysis results indicated that hydrophobic interactions and hydrogen bonds played a major role in the binding process. Site marker competitive experiments and molecular simulation suggested that the probable Bra-binding position was located in subdomain IIA of BSA. UV–vis absorption, circular dichroism (CD) and dynamic light scattering (DLS) experiments suggested the conformational changes of BSA induced by Bra. Additionally, the potential of Bra to inhibit the formation of amyloid fibrils, in vitro, has also been analyzed. Thioflavin T (ThT) binding, 8-anilino-1-naphthalenesulfonic acid (ANS) binding, Congo red binding, DLS, CD, fluorescence microscopic image, atomic force microscopy (AFM), size-exclusion chromatography (SEC) and native gel-electrophoresis methods were used, and all confirmed the anti-amyloidogenic behavior of Bra. In short, our findings have provided some important insights into the binding mechanism of Bra with BSA, and would be helpful in designing suitable agents against amyloid diseases.

Investigation of the binding interactions between 17α-ethinylestradiol with bovine serum albumin by multispectroscopy

To understand the effect of 17α-ethinylestradiol (EE2) on the conformation changes of bovine serum albumin (BSA), the binding mechanisms of EE2 with BSA were investigated by fluorescence spectroscopy, time-resolved fluorescence spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, UV–visible spectroscopy, circular dichroism (CD) spectroscopy and molecular docking. The quenching constants, binding constants, the number of binding sites, thermodynamic parameters, binding distance and the secondary structure changes of BSA were determined. The results of fluorescence quenching experiment suggested that the fluorescence quenching of BSA by EE was due to the formation of complex through static quenching, which was also confirmed by time-resolved fluorescence measurements. The thermodynamic parameters indicated that the binding of EE2 to BSA was driven mainly by van der Waals forces and hydrogen bonding. The conformation alterations of BSA upon EE2 binding were studied by UV–vis spectroscopy and CD spectroscopy. The results of site marker competitive experiments and molecular docking showed that the binding sites of EE2 were mainly located within site I in the subdomain IIA of BSA.

Interaction of xylitol with whey proteins: Multi-spectroscopic techniques and docking studies

This study aimed to examine the interaction mechanism between xylitol (XY) and whey protein isolate (WPI) using multispectral techniques and molecular docking. Additionally, we investigated the effect of XY on WPI functionality using the method of fluorescent probe, high-speed dispersion and differential scanning calorimetry. The fluorescence quenching results such as quenching constants, binding constants and thermodynamic parameters showed strong susceptibility to interacting of WPI and its fractions to XY and the sequence was: α-lactalbumin (α-La) > bovine serum albumin (BSA) > β-lactoglobulin (β-Lg). Docking results revealed that XY was bound to the residues of aromatic cluster II in α-La, the hydrophobic cavity of β-Lg and the subdomain IIA of BSA through hydrogen bonding and van der Waals forces, resulting in conformational changes in secondary structures of proteins, which converted α-helix to β-turn and random coils. Further, XY increased thermal stability and emulsifying properties and reduced surface hydrophobicity and zeta-potential of WPI.

Investigation on the interaction of food colorant Sudan III with bovine serum albumin using spectroscopic and molecular docking methods

Sudan III is a coloring agent used in chemical industries and food additives. This article uses spectroscopic and molecular docking methods to investigate the interaction of Sudan III with bovine serum albumin (BSA) under a physiological condition. Spectroscopic analysis of the emission quenching revealed that the quenching mechanism of BSA by Sudan III was static. The binding sites and constants of Sudan III–BSA complex were observed to be from 0.72 and 6.41 × 102 L·mol−1 to 0.69 and 5.83 × 102 L·mol−1 at 298 and 310 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) revealed that van der Waals forces and hydrogen bonds stabilized the Sudan III–BSA complex. Energy transfer from tryptophan to Sudan III occurred by a fluorescence resonance energy transfer mechanism, and the r distance (3.32 nm) had been determined. The results of UV–Vis absorption, synchronous, three-dimensional fluorescence, and circular dichroism spectra showed that Sudan III induced conformational changes of BSA. Molecular docking studies revealed that Sudan III situated within subdomain IIA of BSA. A study on the interaction between Sudan III and BSA was of fundamental importance for providing more information about the potential toxicological effect of chemicals at the molecular level.

Spectroscopic and molecular docking studies on interaction of two Schiff base complexes with bovine serum albumin

This study was designed to examine interaction of two ternary copper (II) Schiff base complexes with bovine serum albumin (BSA), using spectroscopic and molecular docking techniques. The fluorescence quenching measurements revealed that the quenching mechanism was static and the binding site of both Schiff bases to BSA was singular. Förster energy transfer measurements, synchronous fluorescence spectroscopy, and docking study showed both Schiff bases bind to the Trp residues of BSA in short distances. Docking study showed that both Schiff base molecules bind with BSA by forming several hydrogen and van der Waals bonds. In addition, molecular docking study indicated that Schiff base A and Schiff base B were located within the binding pocket of subdomain IB and subdomain IIA of BSA, respectively. Results of Fourier transform-infrared spectroscopy demonstrated that bovine serum albumin interacts with both Schiff bases and the secondary structure of BSA was changed.Communicated by Ramaswamy H. Sarma

Biochemical and toxicological investigation of karanjin, a bio-pesticide isolated from Pongamia seed oil

Karanjin, a furanoflavonol from Pongamia pinnata L is used in agricultural practices for its pesticidal, insecticidal and acaricidal activities. It is commercially available as a bio-pesticide targeting a wide variety of pests. The present study was intended to evaluate the biochemical interactions of karanjin with bovine serum albumin (BSA) and study its toxicological effects on mammalian and bacterial cell lines. Karanjin bound to BSA at a single site with a dissociation constant of 19.7 μM. Evaluation of BSA-karanjin interactions at three different temperatures indicated the involvement of static mode of quenching. Binding experiments in the presence of warfarin and computational docking analysis indicated that karanjin bound closer to the warfarin binding site located in the Subdomain IIA of BSA. Using Förster resonance energy transfer analysis the distance between TRP 213 of BSA and karanjin was found to be 20 Å. Collective results from synchronous fluorescence spectra analysis, differential scanning calorimetry, and circular dichroism analysis indicated that binding of karanjin induced conformational changes in the secondary structure of BSA. Karanjin exhibited low toxicity against human cervical cancer cells and normal mouse fibroblast L929 cells and modestly inhibited the growth of B. subtilis and E. coli cells. The data presented in this study provides insights for understanding the binding interactions of karanjin with BSA and its possible toxicological effects on mammalian cell lines and bacteria.

Domain-Specific Association of a Phenanthrene-Pyrene-Based Synthetic Fluorescent Probe with Bovine Serum Albumin: Spectroscopic and Molecular Docking Analysis.

In this report, the interaction between a phenanthrene–pyrene-based fluorescent probe (PPI) and bovine serum albumin (BSA), a transport protein, has been explored by steady-state emission spectroscopy, fluorescence anisotropy, far-ultraviolet circular dichroism (CD), time-resolved spectral measurements, and molecular docking simulation study. The blue shift along with emission enhancement indicates the interaction between PPI and BSA. The binding of the probe causes quenching of BSA fluorescence through both static and dynamic quenching mechanisms, revealing a 1:1 interaction, as delineated from Benesi–Hildebrand plot, with a binding constant of ∼105 M–1, which is in excellent agreement with the binding constant extracted from fluorescence anisotropy measurements. The thermodynamic parameters, ΔH°, ΔS°, and ΔG°, as determined from van’t Hoff relationship indicate the predominance of van der Waals/extensive hydrogen-bonding interactions for the binding phenomenon. The molecular docking and site-selective binding studies reveal the predominant binding of PPI in subdomain IIA of BSA. From the fluorescence resonance energy transfer study, the average distance between tryptophan 213 of the BSA donor and the PPI acceptor is found to be 3.04 nm. CD study demonstrates the reduction of α-helical content of BSA protein on binding with PPI, clearly indicating the change of conformation of BSA.

Elucidating the interaction of ticlopidine with serum albumin and its role in bilirubin displacement in vitro

Ticlopidine is an anti-platelet drug that functions as a P2Y12 receptor antagonist. The present study provides a detailed characterization of interaction of ticlopidine with a model transport protein, bovine serum albumin (BSA) as well as an assessment of its bilirubin displacing ability using a multi-spectroscopic approach in combination with isothermal titration calorimetry. The value of binding constant determined using ITC studies was found to be 3.03 × 103 M−1 with a binding stoichiometry of approximately 1:1. Competitive site marker experiments indicate that ticlopidine binds to Sudlow site I, located in subdomain IIA of BSA. In addition, Circular dichroism and 3D fluorescence spectroscopy indicated structural and conformational changes in BSA on interaction with ticlopidine. Thermodynamic parameters suggested that the reaction was spontaneous, exothermic, entropically driven, and involved hydrophobic interactions. These results were well supported by those obtained through molecular docking studies. Additionally, the effect of ticlopidine on bilirubin and albumin interaction was evaluated using the peroxidase method as well as through fluorescence spectroscopy. Ticlopidine was found to displace bilirubin from serum albumin. Moreover, the binding constant of bilirubin–serum albumin interaction also decreased in presence of ticlopidine. The results indicated that ticlopidine is a competitive displacer of bilirubin in vitro and may contribute to the incidences hyperbilirubinemia associated with the usage of this drug.

Spectroscopic and electrochemical studies on the molecular interaction between copper sulphide nanoparticles and bovine serum albumin

The interaction of covellite hexagonal phase of copper sulphide nanoparticles (CuS NPs) with bovine serum albumin (BSA) was examined systematically by using fluorescence, UV–visible, circular dichroism (CD), Fourier transform infrared (FTIR), dynamic light scattering (DLS) and molecular modelling techniques. Electrochemical method was studied to further confirm the interaction of BSA with CuS NPs. The results of fluorescence studies demonstrated that fluorescence of BSA was quenched by CuS NPs via a static quenching mechanism. The negative values of thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the binding process is spontaneous, exothermic and van der Waals force or hydrogen bonding plays major roles in the interaction of CuS NPs with BSA. The interaction of CuS NPs with Trp residue was established by synchronous studies, and competitive binding studies revealed that Trp-212 of subdomain IIA was involved in the interaction with these nanoparticles. Further, the efficiency of energy transferred and the distance between fluorophore (BSA) and acceptor (CuS NPs) were calculated using Forster’s resonance energy transfer theory. The results of UV–visible, CD, FTIR and DLS revealed that the CuS NPs interact with BSA by inducing the conformational changes in secondary structure and reducing the α-helix content of BSA. Molecular modelling studies suggested that CuS NPs bind to site I of sub domain IIA of BSA. The results of spectroscopic and molecular docking studies were complimented by the electrochemical techniques.

Interactions of Bovine Serum Albumin with Anti-Cancer Compounds Using a ProteOn XPR36 Array Biosensor and Molecular Docking

The aim of the work was to determine the interactions of a set of anti-cancer compounds with bovine serum albumin (BSA) using a ProteOn XPR36 array biosensor and molecular docking studies. The results revealed that a total of six anti-cancer compounds: gallic acid, doxorubicin, acteoside, salvianolic acid B, echinacoside, and vincristine were able to reversibly bind to the immobilized BSA. The sensorgrams of these six compounds were globally fit to a Langmuir 1:1 interaction model for binding kinetics analysis. There were significant differences in their affinity for BSA, with doxorubicin, the weakest binding compound having 1000-fold less affinity than salvianolic acid B, the strongest binding compound. However, compounds with a similar KD often exhibited markedly different kinetics due to the differences in ka and kd. Molecular docking experiments demonstrated that acteoside was partially located within sub-domain IIA of BSA, whereas gallic acid bound to BSA deep within its sub-domain IIIA. In addition, the interactions between these compounds and BSA were dominated by hydrophobic forces and hydrogen bonds. Understanding the detailed information of these anti-cancer compounds can provide important insights into optimizing the interactions and activity of potential compounds during drug development.

Intermolecular interaction of nickel (ii) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin: A multi-technique study

ABSTRACTThe interaction of nickel (II) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin (BSA) has been investigated by combination of fluorescence, UV-vis absorption, Fourier transform infrared (FT-IR), and circular dichorism (CD) spectroscopies as well as through molecular docking. Fluorescence quenching and absorption spectra were investigated as a mean for estimating the binding parameters. Analysis of fluorescence quenching data at different temperatures was performed in order to specify the thermodynamics parameters for interactions of phthalocyanine complex with BSA. According to experimental data it was suggested that phthalocyanine had a significant binding affinity to BSA and the process was entropy driven. Based on the results of molecular docking it was indicated that the main active binding site for this phthalocyanine complex is site I in subdomain IIA of BSA. The results provide useful information for understanding the binding mechanism of anticancer drug-albumin and gives insight into the biological activity and metabolism of the drug in blood.

Interactions of two food colourants with BSA: Analysis by Debye-Hückel theory

We have focused on exploring pH- and ionic strength-modulated binding of acid red 1 (AR1) and acid green 50 (AG50) with bovine serum albumin (BSA) by fluorescence, UV–vis absorption and FTIR spectra. The results implied that the quenching mechanism of BSA-AR1/AG50 system was a static quenching, electrostatic force dominated the formation of BSA-AR1/AG50 complex, and the binding affinity of AR1 was greater than that of AG50 on the subdomain IIA of BSA. Moreover, their true thermodynamic binding constant (Keq), true free energy change (ΔG0I→0), and effective charge (ZP) in the anion receptor pocket of BSA were calculated using Debye-Hückel limiting law. The local charge bound by AR1/AG50 rather than the overall or surface charge of BSA played a key role in determining their interaction strength. Besides, the thermal and structural stabilization of BSA was discussed by analyzing the changes of Tm and Hurea without/with the addition of AR1/AG50, respectively.

The Interaction Between Crystal Violet and Bovine Serum Albumin: Spectroscopic and Molecular Docking Investigations

The present work reported the investigations on the interaction between a triphenylmethane industrial dye—crystal violet (CV)—and bovine serum albumin (BSA) by spectroscopic methods and molecular docking calculation. The static quenching mechanism of the intrinsic fluorescence of BSA by CV was deduced by the fluorescence measurements and the ground-state complex formation was confirmed from the UV-vis spectra. The site maker competition binding experiments together with the molecular docking showed that the CV molecule specifically bound on the subdomain IIA of BSA. The obtained values of thermodynamic properties of binding suggested that the hydrophobic interaction was dominated as suggested by molecular docking results that the CV molecule was surrounded by hydrophobic amino acid residues. The conformation change of BSA in the binding process was detected by circular dichroism spectra and Fourier-transform infrared (FTIR) spectra and also reflected by the size change of BSA from the measurements by dynamic light scattering (DLS).

Study on the interaction between pelargonidin-3-O-glucoside and bovine serum albumin using spectroscopic, transmission electron microscopy and molecular modeling techniques.

The aim of this study is to evaluate the binding behavior between pelargonidin-3-O-glucoside (P3G) and bovine serum albumin (BSA) using multi-spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time-resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were -21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α-helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects.

Study on interaction of Ligupurpuroside A with bovine serum albumin by multi-spectroscopic methods

The interaction of Ligupurpuroside A with bovine serum albumin (BSA) has been investigated by fluorescence spectra, UV–vis absorption spectra, three-dimensional (3D) fluorescence spectra, synchronous fluorescence spectra and circular dichroism (CD) spectra along with a molecular docking method. The fluorescence experiments indicate that Ligupurpuroside A can quench the intrinsic fluorescence of BSA through a combined quenching way at the low concentration of Ligupurpuroside A, and a static quenching procedure at the high concentration. The thermodynamic analysis suggests that hydrogen bonds and van der Waals forces are the main forces between BSA and Ligupurpuroside A. According to the theory of Förster׳s non-radiation energy transfer, the binding distance between BSA and Ligupurpuroside A was calculated to be 2.73nm, which implies that energy transfer occurs between BSA and Ligupurpuroside A. All these experimental results have been validated by the protein–ligand docking studies which show that Ligupurpuroside A binds to the residues located in the hydrophobic cavity on subdomain IIA of BSA. In addition, conformation change of BSA was observed from three-dimensional fluorescence spectra, synchronous fluorescence spectra and circular dichroism spectra under experimental conditions.

Molecular interaction of cationic gemini surfactant with bovine serum albumin: A spectroscopic and molecular docking study

Herein, we report the effect of N,N′-bis(dodecyloxycarbonylmethyl)-N,N,N′,N′-tetramethyl-1,2-ethanediammonium dibromide (dodecyl betainate gemini or DBG) on the structure and function of bovine serum albumin (BSA) by using fluorescence, time resolved fluorescence, circular dichroism and dynamic light scattering techniques. The Stern–Volmer quenching constants KSV and the corresponding thermodynamic parameters viz ΔH, ΔG and ΔS have been estimated by the fluorescence quenching method. The results indicated that DBG binds spontaneously with BSA through hydrophobic interaction. Time resolved fluorescence data show that the quenching follows the static mechanism pathway. It can be seen from far-UV CD spectra that the α-helical network of BSA is disrupted and its content increases from 71% to 79% at lower concentrations which again decreases to 38% at higher concentration. DLS measurements suggested that hydrodynamic radius (Rh) decreases in the presence of 30 and 40μM of DBG while it increases when the concentration of DBG was 70 and 100μM. The molecular docking study indicated that DBG is embedded into subdomain IIA of BSA and binds with the R-914, R-195 and R-217 residues by hydrogen bonding and by hydrophobic interaction.

INTERACTION OF RUTHENIUM COMPLEX WITH BOVINE SERUM ALBUMIN FOR AMPEROMETRIC DETECTION OF ASCORBIC ACID

The binding of [Ru(PAN)(PPh3)2(ISN)]Cl (PAN = 1-(2'-Pyridylazo)-2-naphtholate) to bovine serum albumin (BSA) was investigated by spectroscopic techniques. According to analysis of the results from the Stern-Volmer equation, the ruthenium complex is able to quench the fluorescence intensity of BSA via a dynamic mechanism. The thermodynamic parameters were calculated (ΔH = 30.3 kJ mol-1; ΔS = 195.4 J mol-1 K-1), indicating that hydrophobic force is the main interaction driving force. The site marker competitive experiments revealed that the binding site of ruthenium complex was in the sub-domain IIA of BSA. FTO glass with a film of BSA-[Ru(PAN)(PPh3)2(ISN)]Cl was used as an ascorbic acid sensor. The linear range of the modified electrode was between 1 and 8 × 10-6 mol L-1.