Interaction of coomassie brilliant blue G250 with human serum albumin: Probing of the binding mechanism and binding site by spectroscopic and molecular modeling methods

Urease-producing bacteria combined with pig manure biochar immobilize Cd and inhibit the absorption of Cd in lettuce (Lactuca sativa L.)

The synergistic remediation of heavy metal-contaminated soil by functional strains and biochar has been widely studied. However, the mechanisms by which urease-producing bacteria combine with pig manure biochar (PMB) to immobilize Cd and inhibit Cd absorption in vegetables are still unclear. In our study, the effects and mechanisms of PMB combined with the urease-producing bacterium TJ6 (TJ6 + PMB) on Cd adsorption were explored. The effects of TJ6 + PMB on the Cd content and pH of the leachate were also studied through a 56-day soil leaching experiment. Moreover, the effects of the complexes on Cd absorption and microbial mechanisms in lettuce were explored through pot experiments. The results showed that PMB provided strain TJ6 with a greater ability to adsorb Cd, inducing the generation of CdS and CdCO3, and thereby reducing the Cd content (71.1%) and increasing the pH and urease activity in the culture medium. TJ6 + PMB improved lettuce dry weight and reduced Cd absorption. These positive effects were likely due to (1) TJ6 + PMB increased the organic matter and NH4+ contents, (2) TJ6 + PMB transformed available Cd into residual Cd and decreased the Cd content in the leachate, and (3) TJ6 + PMB altered the structure of the rhizosphere bacterial and fungal communities in lettuce, increasing the relative abundances of Stachybotrys, Agrocybe, Gaiellales, and Gemmatimonas. These genera can promote plant growth, decompose organic matter, and release phosphorus. Interestingly, the fungal communities were more sensitive to the addition of TJ6 and PMB, which play important roles in the decomposition of organic matter and immobilization of Cd. In conclusion, this study revealed the mechanism by which urease-producing bacteria combined with pig manure biochar immobilize Cd and provided a theoretical basis for safe pig manure return to Cd-polluted farmland. This study also provides technical approaches and bacterial resources for the remediation of heavy metal-contaminated soil.

Preparation of protein-stabilized Litsea cubeba essential oil nano-emulsion by ultrasonication: Bioactivity, stability, in vitro digestion, and safety evaluation

Litsea cubeba essential oil (LCEO) has garnered widespread attention due to its robust biological activity. However, challenges such as high volatility, limited water solubility, and low bioavailability impede its application. Nano-emulsion encapsulation technology offers an effective solution to these issues. In this study, we prepared litsea cubeba essential oil nano-emulsion (LCEO-NE) for the first time using whey protein (WP) as the emulsifier through an ultrasonic-assisted method, achieving high efficiency with minimal energy consumption. Transmission electron microscopy and dynamic light scattering analyses revealed that the nanoparticles were uniformly spherical, with a particle size of 183.5 ± 1.19 nm and a zeta potential of -35.5 ± 0.95 mV. Stability studies revealed that LCEO-NE exhibited excellent thermal and salt stability, maintaining its integrity for up to four weeks when stored at 4 °C and 25 °C. In vitro digestion assays confirmed the digestibility of LCEO-NE. Furthermore, evaluation of the DPPH, ABTS, and antimicrobial activities revealed that LCEO-NE displayed superior bacteriostatic and antioxidant properties compared to LCEO. Scanning electron microscopy elucidated that its bacteriostatic effect involved the disruption of bacterial microstructure. Hemocompatibility and cytotoxicity assays demonstrated the safety of LCEO-NE within the effective concentration range. This research supports the utilization of nanoparticles for encapsulating LCEO, thereby enhancing its stability and bioactivity, and consequently expanding its applications in the food and pharmaceutical industries.

The changes in iron ions concentration and organic matter composition during the surface microlayer membrane formation process in freshwater

The surface microlayer membrane (SMM) is a complex and unique water body ecosystem. The SMM has a significant effect on water quality and the water ecological system. However, despite the long-lasting interest in the SMM formation process and its environmental effect mechanism in freshwater, studies on it are still scarce. This paper studied the changes in iron ions concentration and organic matter composition during the SMM formation process. Our results revealed that the iron ions enriched in the SMM, at a concentration of up to 8.02 μg/mL, exist in the form of Fe3+. The main organic matter is polysaccharides and proteins in the SMM. Additionally, the microbial community structure revealed that the changes in iron ion morphology in water and the SMM was a significant association with the presence of Aeromonas and Zoogloea. The rapid enrichment process of iron ions and organic matter in the aquatic surface microlayer is involved in the rapid formation of early SMM. Obviously, these findings provide new insights and a basis for the SMM of freshwater.

Development of polyoxyethylene (2) oleyl ether-gliadin nanoparticles: Characterization and in vitro cytotoxicity

Natural polymers have been widely investigated as materials for the delivery of active compounds as a consequence of their biocompatibility, low-cost and the opportunity they furnish to obtain micro- and nanostructures. In this investigation, commercial wheat gliadin was used as raw material with the aim of obtaining a vegetal protein-based nanoformulation to be used for various applications. The influence of non-ionic and anionic surfactants on the physico-chemical properties of gliadin nanoparticles was evaluated in order to propose a suitable candidate able to stabilize the colloidal structure. The use of Super Refined polyoxyethylene (2) oleyl ether gave the best results, promoting the formation of spherical-shaped nanosystems with a narrow size distribution. The oleyl ether-based emulsifier prevented the destabilization of the colloidal systems when pH- and temperature-dependent stress was applied. A freeze-dried formulation was obtained when mannose was used as a cryoprotectant. Polyoxyethylene (2) oleyl ether-stabilized nanosystems were shown to retain and release both hydrophilic and lipophilic model compounds in a controlled manner. The cytotoxicity of the surfactant-free and polyoxyethylene (2) oleyl ether-stabilized gliadin based nanosystems was assessed on human cells, both normal and tumoural, in order to investigate the concentrations of particles that can be used during in vitro experiments. Polyoxyethylene (2) oleyl ether-stabilized gliadin-based nanosystems are promising carriers for the delivery of several active compounds.

Relationship between plankton-based β-carotene and biodegradable adaptablity to petroleum-derived hydrocarbon

Coastal environment are often stress from petroleum-derived hydrocarbon pollution. However, petroleum-derived hydrocarbon is persistent organic pollutants and their biodegradation by phytoplankton is little known. Five species of marine phytoplankton, including Dunaliella salina, Chlorella sp., Conticribra weissflogii, Phaeodactylum tricornutum Bohlin, and Prorocentrum donghaiense, have been used to test their tolerance to petroleum hydrocarbon contamination. D.salina and Chlorella sp can survive in high levels of No. 0 diesel oils water-soluble fractions (WSFs, 5.0 mg L^-1), furthermore, petroleum hydrocarbon could be biodegraded effectively by them (Fig. 2). The content of β-carotene in these two species of phytoplankton has significant correlation with degradation rate of WSFs concentrations (Fig. 4), petroleum hydrocarbons could be biodegraded effectively by algae. Meanwhile, the ·OH in seawater can be removed by β-carotene effectively so that algal cells could be protected by the β-carotene for its strong antioxidant capacity. Therefore, β-carotene as a coin has two sides on the degradation of WSFs. Here we explore the relationship between plankton-based β-carotene and biodegradable adaptabllity to petroleum-derived hydrocarbon, which offers a green technology for petroleum-derived hydrocarbon treatment.

Methods of albumin estimation in clinical biochemistry: Past, present, and future

Estimation of serum and urinary albumin is routinely performed in clinical biochemistry laboratories. In the past, precipitation-based methods were popular for estimation of human serum albumin (HSA). Currently, dye-binding or immunochemical methods are widely practiced. Each of these methods has its limitations. Research endeavors to overcome such limitations are on-going. The current trends in methodological aspects of albumin estimation guiding the field have not been reviewed. Therefore, it is the need of the hour to review several aspects of albumin estimation. The present review focuses on the modern trends of research from a conceptual point of view and gives an overview of recent developments to offer the readers a comprehensive understanding of the subject.

Multi-spectroscopic and molecular modeling studies of interaction between two different angiotensin I converting enzyme inhibitory peptides from gluten hydrolysate and human serum albumin

The present study was carried out to characterize Angiotensin-converting enzyme (ACE) inhibitory peptides which are released from the trypsin hydrolysate of wheat gluten protein. The binding of two inhibitory peptide (P₄ and P₆) to human serum albumin (HSA) under physiological conditions has been investigated by multi-spectroscopic in combination with molecular modeling techniques. Time-resolved and quenching fluorescence spectroscopies results revealed that the quenching of HSA fluorescence by P₄ and P₆ in the binary and ternary systems caused HSA-peptides complexes formation. The results indicated that both peptides quenched the fluorescence intensity of HSA through a static mechanism. The binding affinities and number of binding sites were obtained for the HSA-peptides complexes. The circular dichroism (CD) data revealed that the presence of both peptides increased the α-helix content of HSA and induced the remarkable folding of the polypeptide of the protein. Therefore, the CD data determined that the protein structure has been stabilized in the percent of ACE inhibitory peptides in binary and ternary systems. The binding distances between HSA and both peptides were estimated by the Forster theory, and it was revealed that nonradiative energy transfer from HSA to peptides occurred with a high probability. ITC experiments reveal that, in the absence and presence of P₆, the dominant forces are electrostatic in binary and ternary systems. Furthermore, molecular modeling studies confirmed the experimental results. Molecular modeling investigation suggested that P₄ bound to the site IA and IIA of HSA in binary and ternary systems, respectively. This study on the interaction of peptides with HSA should prove helpful for realizing the distribution and transportation of food compliments and drugs in vivo, elucidating the action mechanism and dynamics of food compliments and drugs at the molecular level. It should moreover be of great use for understanding the pharmacokinetic and pharmacodynamic mechanism of the food compliments and drugs.

Molecular insight into the Grandivitin- matrix metalloproteinase 9 interactions

Grandivitin (GRA), a natural coumarin, can inhibit Matrix metalloproteinase 9 (MMP9). Binding characteristics are therefore of interest for pharmacodynamics of GRA and coumarin derivatives. A combination of spectroscopic methods and molecular modeling techniques was used to characterize interaction of GRA with MMP9. Fluorescence spectroscopy showed that GRA could quench the MMP9 fluorescence spectra. Changes in the UV-Vis and FT-IR spectra were observed upon ligand binding along with a significant degree of tryptophan fluorescence quenching on complex formation. Fluorescence studies showed that GRA has an ability to quench the intrinsic fluorescence of MMP9. Molecular modeling analysis showed that GRA to be bound in the large hydrophobic cavity of MMP9. Further investigation of the binding site of GRA within the MMP9 molecule suggested that hydrophobic contacts, hydrogen bond formation and electrostatic interactions account for the binding of GRA. According molecular dynamics (MD) simulation results the ligand can interact with the protein, with affecting the secondary structure of MMP9 and with a modification of its tertiary structure. The biological significance of this work is evident because MMP9 serves as a potential target protein for anticancer agents. The binding study of GRA with MMP9 is of great importance in pharmacy, pharmacology and biochemistry. This work can provide some key data to clinical research and supply the theoretical basis for the new drug candidate designing.

Hydrogen bonding plays a significant role in the binding of coomassie brilliant blue-R to hemoglobin: FT-IR, fluorescence and molecular dynamics studies

Coomassie brilliant blue-R (CBB-R) specifically binds to bovine hemoglobin with a stoichiometric ratio of 1 : 1.

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.

Risk assessment of nitrate and petroleum-derived hydrocarbon addition on Contricriba weissflogii biomass, lifetime, and nutritional value

Coastal diatoms are often exposed to both petroleum-derived hydrocarbon pollution and eutrophication. How these exposures influence on algal biomass, lifetime, and nutritional value are unknown. To examine a more accurate risk assessment of the pollutants on the role of diatoms in coastal ecosystem functions, Conticribra weissflogii was maintained at different concentrations of nitrate (N) and/or water-soluble fractions of No.0 diesel oil (WSF). Algal density, cell growth cycle, protein, chlorophyll a, superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were determined for the assessment of algal biomass, lifetime, nutritional value, photosynthesis and respiration, antioxidant capacity, and lipid peroxidation, respectively.When N addition was combined with WSF pollution, the cell growth cycles were shortened by 27-44%; SOD activities were decreased by 1-64%; algal density, the concentrations of chlorophyll a, protein, and MDA were varied between 38 and 310%, 62 and 712%, 4 and 124%, and 19 and 233% of the values observed in N addition experiments, respectively. Coastal ecosystem functions were severely weakened by N and WSF additions, and the influence was increased in the order: N<WSF<WSF+N. Thus, the simultaneous monitoring of N and WSF was necessary for the risk assessment of petroleum-derived hydrocarbon on coastal ecosystem functions.

Risk assessment of nitrate and oxytetracycline addition on coastal ecosystem functions

Diatoms dominate phytoplankton communities in the well-mixed coastal and upwelling regions. Coastal diatoms are often exposed to both aquaculture pollution and eutrophication. But how these exposures influence on coastal ecosystem functions are unknown. To examine these influences, a coastal centric diatom, Conticribra weissflogii was maintained at different concentrations of nitrate (N) and/or oxytetracycline (OTC). Algal density, cell growth cycle, protein, chlorophyll a, superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were determined for the assessment of algal biomass, lifetime, nutritional value, photosynthesis and respiration, antioxidant capacity, and lipid peroxidation, respectively. When N addition was combined with OTC pollution, the cell growth cycles were shortened by 56-73%; algal density, SOD activities, the concentrations of chlorophyll a, protein, and MDA varied between 73 and 121%, 19 and 397%, 52 and 693%, 19 and 875%, and 66 and 2733% of the values observed in N addition experiments, respectively. According to P-value analysis, the influence of OTC on algal density and SOD activity was not significant, but the effect on cell growth cycle, protein, chlorophyll a, and MDA were significant (P<0.05). The influence of N addition with simultaneous OTC pollution on the above six end points was significant. Algal biomass, lifetime, nutrition, antioxidant capacity, lipid peroxidation, photosynthesis, and respiration were all affected by the addition of OTC and N. Coastal ecosystem functions were severely affected by N and OTC additions, and the influence was increased in the order: N<OTC<OTC+N. Thus, the simultaneous monitoring of N and OTC was necessary for the risk assessment of aquaculture pollution on coastal ecosystem functions.

Intermolecular interaction of prednisolone with bovine serum albumin: spectroscopic and molecular docking methods

The intermolecular interaction of prednisolone with bovine serum albumin (BSA) was studied using fluorescence, circular dichroism (CD) and molecular docking methods. The experimental results showed that the fluorescence quenching of the BSA at 338 nm by prednisolone resulted from the formation of prednisolone-BSA complex. The number of binding sites (n) for prednisolone binding on BSA was approximately equal to 1. Base on the sign and magnitude of the enthalpy and entropy changes (ΔH(0)=-149.6 kJ mol(-1) and ΔS(0)=-370.7 J mol(-1)K(-1)) and the results of molecular docking, it could be suggested that the interaction forces were mainly Van der Waals and hydrogen bonding interactions. Moreover, in the binding process of BSA with prednisolone, prednisolone molecule can be inserted into the hydrophobic cavity of subdomain IIIA (site II) of BSA. The distance between prednisolone and Trp residue of BSA was calculated as 2.264 nm according to Forster's non-radiative energy transfer theory.

Spectral characterization of the binding and conformational changes of serum albumins upon interaction with an anticancer drug, anastrozole

The present study employed different optical spectroscopic techniques viz., fluorescence, FTIR, circular dichroism (CD) and UV-vis absorption spectroscopy to investigate the mechanism of interaction of an anticancer drug, anastrozole (AZ) with transport proteins viz., bovine serum albumin (BSA) and human serum albumin (HSA). The drug, AZ quenched the intrinsic fluorescence of protein and the analysis of results revealed the presence of dynamic quenching mechanism. The binding characteristics of drug-protein were computed. The thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°) were calculated to be +92.99 kJ/mol and +159.18 J/mol/K for AZ-BSA and, +99.43 kJ/mol and +159.19 J/mol/K for AZ-HSA, respectively. These results indicated that the hydrophobic forces stabilized the interaction between the drug and protein. CD, FTIR, absorption, synchronous and 3D fluorescence results indicated that the binding of AZ to protein induced structural perturbation in both serum albumins. The distance, r between the drug and protein was calculated based on the theory of Förster's resonance energy transfer and found to be 5.9 and 6.24 nm, respectively for AZ-BSA and AZ-HSA.

Use of spectroscopic, zeta potential and molecular dynamic techniques to study the interaction between human holo-transferrin and two antagonist drugs: comparison of binary and ternary systems

For the first time, the binding of ropinirole hydrochloride (ROP) and aspirin (ASA) to human holo-transferrin (hTf) has been investigated by spectroscopic approaches (fluorescence quenching, synchronous fluorescence, time-resolved fluorescence, three-dimensional fluorescence, UV-vis absorption, circular dichroism, resonance light scattering), as well as zeta potential and molecular modeling techniques, under simulated physiological conditions. Fluorescence analysis was used to estimate the effect of the ROP and ASA drugs on the fluorescence of hTf as well as to define the binding and quenching properties of binary and ternary complexes. The synchronized fluorescence and three-dimensional fluorescence spectra demonstrated some micro-environmental and conformational changes around the Trp and Tyr residues with a faint red shift. Thermodynamic analysis displayed the van der Waals forces and hydrogen bonds interactions are the major acting forces in stabilizing the complexes. Steady-state and time-resolved fluorescence data revealed that the fluorescence quenching of complexes are static mechanism. The effect of the drugs aggregating on the hTf resulted in an enhancement of the resonance light scattering (RLS) intensity. The average binding distance between were computed according to the forster non-radiation energy transfer theory. The circular dichroism (CD) spectral examinations indicated that the binding of the drugs induced a conformational change of hTf. Measurements of the zeta potential indicated that the combination of electrostatic and hydrophobic interactions between ROP, ASA and hTf formed micelle-like clusters. The molecular modeling confirmed the experimental results. This study is expected to provide important insight into the interaction of hTf with ROP and ASA to use in various toxicological and therapeutic processes.

Spectroscopic and molecular modeling studies on the interaction between a fluorine-containing triazole derivative and human serum albumin

The interaction between 4-(4-fluorobenzylideneamino)-5-propyl-4H-1,2,4-triazole-3-thiol (FBTZ) and human serum albumin (HSA) under simulative physiological conditions was investigated by fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy as well as molecular modeling method. Fluorescence spectroscopic data showed that the fluorescence quenching of HSA was a result of the formation of FBTZ-HSA complex. According to the modified Stern-Volmer equation, the effective quenching constants (K (a)) of FBTZ to HSA were obtained at three different temperatures. The enthalpy change (ΔH) and entropy change (ΔS) were calculated on the basis of van't Hoff equation, and the results showed that hydrogen-bonding and van der Waals forces were the dominant intermolecular forces to stabilize the complex. Site marker competitive replacement experiments demonstrated that the binding of FBTZ to HSA primarily took place in sub-domain IIA (Sudlow's site I). The binding distance (r) between FBTZ and the tryptophan residue of HSA was estimated according to the theory of fluorescence resonance energy transfer. The conformational investigation showed that the presence of FBTZ induced some changes of secondary structure of HSA. Molecular modeling study further confirmed the binding mode obtained by experimental study.