Binding of serum albumins with bioactive substances – Nanoparticles to drugs

Synthesis and crystal structure elucidation of new copper(II)-based chemotherapeutic agent coupled with 1,2-DACH and orthovanillin: Validated by in vitro DNA/HSA binding profile and pBR322 cleavage pathway

New copper(II)-based complex (1) was synthesized and characterized by analytical, spectroscopic and single crystal X-ray diffraction. The in vitro binding studies of complex 1 with CT DNA and HSA have been investigated by employing biophysical techniques to examine the binding propensity of 1 towards DNA and HSA. The results showed that 1 avidly binds to CT DNA via electrostatic mode along with the hydrogen bonding interaction of NH2 and CN groups of Schiff base ligand with the base pairs of DNA helix, leads to partial unwinding and destabilization of the DNA double helix. Moreover, the CD spectral studies revealed that complex 1 binds through groove binding interaction that stabilizes the right-handed B-form of DNA. Complex 1 showed an impressive photoinduced nuclease activity generating single-strand breaks in comparison with the DNA cleavage activity in presence of visible light. The mechanistic investigation revealed the efficiency of 1 to cleave DNA strands by involving the generation of reactive oxygen species. Furthermore, the time dependent DNA cleavage activity showed that there was gradual increase in the amount of NC DNA on increasing the photoexposure time. However, the interaction of 1 and HSA showed that the change of intrinsic fluorescence intensity of HSA was induced by the microenvironment of Trp residue.

Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) exhibits significant antitumor activity. However, the mechanism of its pharmacological interaction with human serum albumin (HSA) and DNA remains poorly understood. Here, we aimed to elucidate the interactions of Dp44mT with HSA and DNA using MTT assays, spectroscopic methods, and molecular docking analysis. Our results indicated that addition of HSA at a ratio of 1:1 did not alter the cytotoxicity of Dp44mT, but did affect the cytotoxicity of the Dp44mT-Cu complex. Data from fluorescence quenching and UV-VIS absorbance measurements demonstrated that Dp44mT could bind to HSA with a moderate affinity (K_a = approximately 10⁴ M⁻¹). CD spectra revealed that Dp44mT could slightly disrupt the secondary structure of HSA. Dp44mT could also interact with Ct-DNA, but had a moderate binding constant (K_EB = approximately 10⁴ M⁻¹). Docking studies indicated that the IB site of HSA, but not the IIA and IIIA sites, could be favorable for Dp44mT and that binding of Dp44mT to HSA involved hydrogen bonds and hydrophobic force, consistent with thermodynamic results from spectral investigations. Thus, the moderate binding affinity of Dp44mT with HSA and DNA partially contributed to its antitumor activity and may be preferable in drug design approaches.

Structure-activity relationship study between baicalein and wogonin by spectrometry, molecular docking and microcalorimetry

Flavones (e.g. baicalein and wogonin) extensively used worldwide in food preparation and traditional medicine. In this study, a systematically comparative study of their structure-activity relationships (SAR) on their interaction with BSA, antioxidant activity and antibacterial activity has been carried out by spectrometry, molecular docking and microcalorimetry. Our results show that the skeleton structure of flavones, the number of hydroxyl groups, the type of functional group, conjugated system and the steric hindrance may be responsible for their different biological activity. These findings not only would lay a scientific foundation for discovering and designing flavones-based food and drug, may also help us to understanding the structure-activity relationship between flavones at the molecular level.

Interactions of 1-hydroxypyrene with bovine serum albumin: insights from multi-spectroscopy, docking and molecular dynamics simulation methods

Combining multi-spectroscopy, docking with MD simulations, the interactions of 1-hydroxypyrene with BSA and the adverse effects on BSA were investigated.

Comparative binding study of anti-tuberculosis drug pyrazinamide with serum albumins

The interaction of anti-tuberculosis drug pyrazinamide (PYZ) with serum albumins (HSA and BSA) has been studied using spectroscopic and molecular docking approaches.

Insights into the binding of photothermal therapeutic agent bismuth sulfide nanorods with human serum albumin

The interaction of microwave synthesized bismuth sulfide nanorods with human serum albumin was investigated using multispectroscopic techniques such as absorption spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy.

Synthesis and crystal structure determination of a mononuclear cobalt(ii) complex derived from 4-(pyridin-4-ylmethoxy)-benzoic acid: evaluation of the DNA/protein interaction and photo-induced pBR322 DNA cleavage

New Co(ii)-based chemotherapeutic drug candidate was synthesized and thoroughly characterized by spectroscopic, analytical and single crystal X-ray techniques.

Unraveling the binding interaction of Toluidine blue O with bovine hemoglobin – a multi spectroscopic and molecular modeling approach

Toluidine blue O (TBO) is a cationic photosensitizer that belongs to the class of phenothiazinium dyes.

Study of the structure-activity relationship of flavonoids based on their interaction with human serum albumin

The influence of functional groups on the interaction has been studied detailed here; fluorescence quenching degrees and the conformation change are considered through multiple methods; molecular docking has been introduced to verify related results.

Development and application of a label-free fluorescence method for determining the composition of gold nanoparticle-protein conjugates

A method was developed for determining the composition of the conjugates between gold nanoparticles and proteins based on the intrinsic fluorescence of unbound protein molecules. The fluorescence was evaluated after separation of the conjugates from the reaction mixture by centrifugation. Gold nanoparticles obtained using the citrate technique (average diameter 24 nm) were conjugated at pH 5.4 with the following four proteins: human immunoglobulin G (IgG), bovine serum albumin (BSA), recombinant streptococcal protein G (protein G), and Kunitz-type soybean trypsin inhibitor (STI). The compositions of these conjugates were determined using the developed method. The conjugate compositions were dependent on the concentration of the added protein, and in all cases reached saturation. The equilibrium dissociation constants of the gold nanoparticle conjugates with IgG, BSA, protein G, STI in the initial section of the concentration dependence curve were 4, 6, 10, and 15 nM, respectively. Close to saturation, the corresponding values were 25, 76, 175, and 100 nM, respectively. The maximal binding capacities of a single gold nanoparticle for IgG, BSA, Protein G, and STI were 52, 90, 500, and 550, respectively, which agrees well with the hypothesis of monolayer immobilization.

Potential toxicity of amphenicol antibiotic: binding of chloramphenicol to human serum albumin

Antibiotics are widely used in daily life but their abuse has posed a potential threat to human health. To evaluate the toxicity of chloramphenicol (CAP) at the protein level, the interaction between CAP and human serum albumin (HSA) was investigated by fluorescence, Ultraviolet-visible (UV-Vis) absorption, Fourier transform infrared (FT-IR) spectroscopy and molecular docking methods. Fluorescence data revealed that the fluorescence quenching of HSA by CAP was the result of the formation of CAP-HSA complex, and the binding constant was determined to be 3.196 × 10(4) L mol(-1) at 310 K. The thermodynamic determination indicated that the interaction was driven by enthalpy change and entropy change together, where the multiple hydrogen bonds (CAP and the residues Arg 222 and His 242 of HSA) and van der Waals forces were the dominant binding force. The site marker competition revealed that CAP bound into sub-domain IIA of HSA. The binding of CAP induced the drastic reduction in α-helix conformation and the significant enhancement in β-sheet conformation of HSA. Molecular docking study further confirmed the binding mode obtained by experimental study. This work provides a new quantitative evaluation method for antibiotics to cause the protein damage.

Experimental and theoretical investigation on the interaction between cyclovirobuxine D and human serum albumin

Cyclovirobuxine D is an active compound extracted from the plant Buxux microphylla, and widely available as medications; however, its abuse may casts potential detrimental effects on human health. By using multispectroscopic techniques and molecular modeling, the interaction of cyclovirobuxine D with human serum albumin was investigated. The fluorescence results manifested that static type was the operative mechanism for the interaction with human serum albumin. The structural investigation of the complexed HSA through CD, three-dimensional, FT-IR and synchronous fluorescence shown the polypeptide chain of HSA partially destabilizing. Docking studies revealed the molecule to be bound in the subdomain IIA. Finally, we investigated the distance between the bound ligand and Trp-214 of human serum albumin.

Morphological analysis and interaction of chlorophyll and BSA

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

A fluorescence anisotropy method for measuring protein concentration in complex cell culture media

The rapid, quantitative analysis of the complex cell culture media used in biopharmaceutical manufacturing is of critical importance. Requirements for cell culture media composition profiling, or changes in specific analyte concentrations (e.g. amino acids in the media or product protein in the bioprocess broth) often necessitate the use of complicated analytical methods and extensive sample handling. Rapid spectroscopic methods like multi-dimensional fluorescence (MDF) spectroscopy have been successfully applied for the routine determination of compositional changes in cell culture media and bioprocess broths. Quantifying macromolecules in cell culture media is a specific challenge as there is a need to implement measurements rapidly on the prepared media. However, the use of standard fluorescence spectroscopy is complicated by the emission overlap from many media components. Here, we demonstrate how combining anisotropy measurements with standard total synchronous fluorescence spectroscopy (TSFS) provides a rapid, accurate quantitation method for cell culture media. Anisotropy provides emission resolution between large and small fluorophores while TSFS provides a robust measurement space. Model cell culture media was prepared using yeastolate (2.5 mg mL(-1)) spiked with bovine serum albumin (0 to 5 mg mL(-1)). Using this method, protein emission is clearly discriminated from background yeastolate emission, allowing for accurate bovine serum albumin (BSA) quantification over a 0.1 to 4.0 mg mL(-1) range with a limit of detection (LOD) of 13.8 μg mL(-1).

Synthesis, structure elucidation and DFT studies of a new coumarin-derived Zn(ii) complex: in vitro DNA/HSA binding profile and pBR322 cleavage pathway

A new mononuclear coumarin-derived Zn(ii) complex was designed and synthesized, and its interactions with DNA and protein were analyzed.

In vitro investigation of domain specific interactions of phenothiazine dye with serum proteins by spectroscopic and molecular docking approaches

In the present study the interaction of the chemotherapeutic agent, Azure A (AZA) with Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) was investigated by multi spectroscopic and molecular docking methods.

Influence of glucuronidation and reduction modifications of resveratrol on its biological activities

Resveratrol (3,5,4'-trihydroxystilbene, RES), a star among dietary polyphenols, shows a wide range of biological activities, but it is rapidly and extensively metabolized into its glucuronide and sulfate conjugates as well as to the corresponding reduced products. This begs the question of whether the metabolites of RES contribute to its in vivo biological activity. To explore this possibility, we synthesized its glucuronidation (3-GR and 4'-GR) and reduction (DHR) metabolites, and evaluated the effect of these structure modifications on biological activities, including binding ability with human serum albumin (HSA), antioxidant activity in homogeneous solutions and heterogeneous media, anti-inflammatory activity, and cytotoxicity against various cancer cell lines. We found that 1) 4'-GR, DHR and RES show nearly equal binding to HSA, mainly through hydrogen bonding, whereas 3-GR adopts a quite different orientation mode upon binding, thereby resulting in reduced ability; 2) 3-GR shows comparable (even equal) ability to RES in FRAP- and AAPH-induced DNA strand breakage assays; DHR, 3-GR, and 4'-GR exhibit anti-hemolysis activity comparable to that of RES; additionally, 3-GR and DHR retain some degree activity of the parent molecule in DPPH.-scavenging and cupric ion-initiated oxidation of LDL assays, respectively; 3) compared to RES, 4'-GR displays equipotent ability in the inhibition of COX-2, and DHR presents comparable activity in inhibiting NO production and growth of SMMC-7721 cells. Relative to RES, its glucuronidation and reduction metabolites showed equal, comparable, or some degree of activity in the above assays, depending on the specific compound and test model, which probably supports their roles in contributing to the in vivo biological activities of the parent molecule.

Binding, unfolding and refolding dynamics of serum albumins

BACKGROUND

The serum albumins (human and bovine serum albumin) occupy a seminal position among all proteins investigated until today as they are the most abundant circulatory proteins. They play the major role of a transporter of many bio-active substances which include various fatty acids, drug molecules, and amino acids to the target cells. Hence, studying the interaction of these serum albumins with different binding agents has attracted enormous research interests from decades. The nature and magnitude of these bindings have direct consequence on drug delivery, pharmacokinetics, therapeutic efficacy and drug design and control.

SCOPE OF THE REVIEW

In the present review, we summarize the binding characteristics of both the serum albumins with surfactants, lipids and vesicles, polymers and dendrimers, nanomaterials and drugs. Finally we have reviewed the effect of various chemical and physical denaturants on these albumins with a special emphasis on protein unfolding and refolding dynamics.

MAJOR CONCLUSIONS

The topic of binding and dynamics of protein unfolding and refolding spans across all areas of inter-disciplinary sciences and will benefit clinical toxicology and medicines. The extensive data from several contemporary research based on albumins will help us to understand protein dynamics in a more illustrious manner.

GENERAL SIGNIFICANCE

These data have immense significance in understanding and unravelling the mechanisms of protein unfolding/refolding and thus can pave the way to prevent protein mis-folding/aggregation which sometimes leads to severe consequences like Parkinson's and Alzheimer's diseases. This article is a part of a Special Issue entitled Serum Albumin. This article is part of a Special Issue entitled Serum Albumin.