Conformation Of Albumin Research Articles

Albumin Folding Changes Affect the Microfluidic Interfacial Broadening Revealed by Surface Plasmon Resonance

AbstractUnderstanding the conformation and diffusion behavior of proteins in biological fluids is crucial for advancements in conformational disease research. While several experimental techniques are available for probing protein conformations, they often come with limitations, such as the need for fluorophores or specific experimental conditions. Albumin, one of the most abundant proteins in the blood and used as a tear supplement in treating ocular surface disorders, plays a vital role as a transport protein, binding various ligands and facilitating their transport. However, the direct relationship between albumin conformation and diffusion coefficient (D) in water solutions remains unexplored. In this study, we describe a novel Surface Plasmon Resonance technique coupled with Stochastic Gillespie′s algorithm simulations to correlate albumin D values with its conformational states directly. Our findings demonstrate the feasibility of monitoring albumin conformational changes under different environmental conditions, as well as its degradation kinetics by trypsin, by analyzing its diffusion characteristics, presenting a promising avenue for advancing our understanding of conformational diseases.

Evaluating the antioxidant, anti-inflammatory, and neuroprotective potential of fruiting body and mycelium extracts from edible yellow morel (Morchella esculenta L. Pers.).

This study aimed to assess the antioxidant, anti-inflammatory, and acetylcholinesterase activities of fruiting bodies (FB) and mycelium (M) extracts of Morchella esculenta L. collected from various regions of Pakistan. The samples included Skardu fruiting body (SKFB) and mycelia Skardu (SKM), Malam Jaba fruiting body (MJFB) and Malam Jaba mycelia (MJM), Krair Mansehra fruiting body (KMFB) and Krair Mansehra mycelia (KMM), and Thandiani fruiting body (TFB) and Thandiani mycelia (TM). The IC50 values for free radical scavenging activity of all samples revealed that fruiting body SKFB and MJFB of M. esculenta are significantly involved in relieving oxidative stress. Bovine serum albumin conformation destruction assay showed a significantly increased anti-inflammatory activity of SKFB with an IC50 value of 10.94±0.098 µg/mL. The human red blood cell protection assay showed that TFB has a lower EC50 value as compared to other samples. KMFB and KMM extracts of M. esculenta showed significantly higher anti-acetylcholinesterase activity compared to the standard drug, donepezil. The lower IC50 value of M. esculenta extracts suggested higher efficacy for acetylcholinesterase (AChE) inhibition. Enzyme kinetics results showed that KMFB of M. esculenta is a competitive inhibitor, while KMM and Donepezil are noncompetitive AChE inhibitors. Further, molecular docking, physicochemical properties and ADMET analysis of M. esculenta constituents showed smooth drug diffusion and protection against neurodegenerative disorders. This study indicates that M. esculenta extracts may hold significant therapeutic potential for neurodegenerative diseases, opening a path for potential therapeutic strategies.

Effect of Acetonitrile on the Conformation of Bovine Serum Albumin.

The use of organic solvents in drug delivery systems (DDSs) either to produce albumin nanoparticles or to manipulate the binding of target molecules to albumin, a promising nanocarrier material, presents challenges due to the conformational changes induced in the protein. In this study, we investigated the alterations in the conformation of bovine serum albumin (BSA) caused by acetonitrile (ACN) in aqueous solution by using a combination of spectroscopic analysis and molecular dynamics (MD) simulations. Ultraviolet (UV) absorption, fluorescence, and infrared (IR) absorption spectroscopy were used to analyze the BSA conformation in the solutions containing 0-60 vol % ACN. Additionally, MD simulations were conducted to elucidate the interactions between BSA and solvent components, focusing on the structural changes in the hydrophobic pocket with Trp residues of the albumin. Increasing the ACN concentration leads to significant changes in the BSA conformation, as evidenced by shifts in UV fluorescence wavelength, decreased intensity, and alterations in IR absorption bands. Furthermore, the formation of protein aggregates was observed at high ACN concentration (30 vol % ACN), shown by increased hydrodynamic diameter distribution. MD simulations further demonstrate that the presence of ACN molecules near the hydrophobic pocket with the Trp-213 residue increases the fluctuations in the positions of amino acids observed near the hydrophobic pocket with Trp-213. Moreover, the intrusion of water molecules into the hydrophobic pocket under 60% ACN conditions with highly decreased solvent polarity was correlated with the changes in the BSA secondary structure. These findings enhance our understanding of how solvent polarity affects the albumin conformation, which is crucial for optimizing albumin-based DDS applications.

Effect of the Protein Chain Conformation on the Collapse into Nanoparticles.

Protein single-chain nanoparticles can outperform synthetic nanoparticles in biomedical applications due to enhanced biocompatibility. Compared to synthetic (co)polymers, the chemical complexity of proteins challenges chain conformation control. Here, we investigate the impact of the precursor chain conformation of bovine serum albumin (BSA) on the nanoparticle structure after intramolecular cross-linking. We explore the urea concentration (denaturant), pH, salt, cross-linker length, and concentration. Small-angle neutron scattering and dynamic light scattering experiments reveal a shrinking chain conformation upon cross-linking. However, the ability to collapse depends on solvent conditions: more expanded chains collapse more, whereas proteins that are already compact barely change in size upon cross-linking. Static light scattering measurements demonstrate that binding is primarily intramolecular. The use of a shorter cross-linker does not lead to collapse of extended chains. Overall, BSA exhibits a similar behavior to that of polymer nanoparticles, which then allows to harness the precursor conformation for morphological control.

Analysis of the effect of cations on protein conformational stability using solid-state nanopores.

The conformation of proteins is closely related to their biological functions, and it is affected by many factors, including the type of cations in solution. However, it is difficult to detect the conformational changes of a protein in situ. As a single-molecule sensing technology, nanopores can convert molecular structural information into analyzable current signals within a reasonable time range. Herein, we detect and analyze the effects of two different types of monovalent cations (Na+ and Li+) on a model protein bovine serum albumin (BSA) conformation using SiNx nanopores with different diameters. The quantitative analysis results show that the excluded volume of BSA in LiCl salt solutions is larger than the value in NaCl solution, indicating that Li+ is more prone to unfolding the proteins and making them unstable. This study demonstrated that nanopores enable the in situ detection of the structure of proteins at the single-molecule level and provide a new approach for the quantitative analysis of proteins.

Influence of para-substituted benzaldehyde derivatives with different push/pull electron strength groups on the conformation of human serum albumin and toxicological effects in zebrafish

Excessive intake of benzaldehyde and its derivatives can cause irreversible damage to living organisms. Hence, benzaldehyde derivatives with different para-substitutions of push/pull electronic groups were chosen to investigate the effect of different substituent properties on the structure of human serum albumin (HSA). The binding constants, number of binding sites, major interaction forces, protein structural changes, and binding sites of benzaldehyde (BzH) and its derivatives (4-BzHD) with HSA in serum proteins were obtained based on multispectral and molecular docking techniques. The mechanism of BzH/4-BzHD interaction on HSA is mainly static quenching and is accompanied by the formation of a ground state complex. BzH/4-BzHD is bound to HSA in a 1:1 stoichiometric ratio. The interaction forces for the binding of BzH/4-BzHD to HSA are mainly hydrogen bonding and hydrophobic interaction, which are also accompanied by a small amount of electrostatic interactions. The effect of BzH/4-BzHD on HSA conformation follows: 4-Diethylaminobenzaldehyde (4-DBzH) > 4-Nitrobenzaldehyde (4-NBzH) > 4-Hydroxybenzaldehyde (4-HBzH) > 4-Acetaminobenzaldehyde (4-ABzH) > BzH, which means that the stronger push/pull electronic strength of the para-substituted benzaldehyde derivatives has a greater effect on HSA conformation. Furthermore, the concentration-lethality curves of different concentrations for BzH/4-BzHD on zebrafish verified above conclusion. This work provides a scientific basis for the risk assessment of benzaldehyde and its derivatives to the ecological environment and human health and for the environmental toxicological studies of benzaldehyde derivatives with different strengths of push/pull electron substitution.

The effect of chrysin binding on the conformational dynamics and unfolding pathway of human serum albumin

Studies on the interactions between ligands and proteins provide insights into how a possible medication alters the structures and activities of the target or carrier proteins. The natural flavonoid aglycone Chrysin (CHR) has demonstrated anti-inflammatory, antioxidant, antiapoptotic, neuroprotective, and antineoplastic effects, both in vitro and in vivo. In this work, we investigated the impact of CHR binding on the as-yet-unexplored conformation, dynamics, and unfolding mechanism of human serum albumin (HSA). We determined CHR binding to HSA domain-II with the association constant (Ka) of 2.70 ± 0.21 × 105 M−1. The urea-induced sequential unfolding mechanism of HSA was used to elucidate the debatable binding location of CHR. CHR binding induced both secondary and tertiary structural alterations in the protein as studied by far-UV circular dichroism and intrinsic fluorescence spectroscopy. Red edge excitation shift (REES) indicated a decrease in conformational dynamics of the protein on the complex formation. This suggested an ordered compact and spatial arrangement of the CHR-boundmolecule. The binding of CHR was found to significantly modulate the urea-induced unfolding pathway of HSA. Urea-induced unfolding pathway of HSA became a two-state process (N-U) from a three-state process (N-I-U). The interaction of CHR is found to increase the thermal stability of the protein by ∼4 °C. This study focuses on the fundamental sciences and demonstrates how prospective medication compounds can alter the dynamics and stability of protein structure.

Anxious and melancholic depression are followed by differently directed serum albumin conformation

Anxious and melancholic depression are followed by differently directed serum albumin conformation

Anxious and Melancholic Depression Are Associated with Oppositely Directed Changes in Serum Albumin Conformation

Anxious and Melancholic Depression Are Associated with Oppositely Directed Changes in Serum Albumin Conformation

Pillar[5]arene/albumin biosupramolecular systems for simultaneous native protein preservation and encapsulation of a water-soluble substrate.

The growing resistance of pathogens, bacteria, viruses, and fungi to a number of drugs has encouraged researchers to use natural and synthetic biomimetic systems to overcome this challenge. Multicomponent systems are an attractive approach for drug design and multitarget therapy. In this study, we report the assembly of a three-component (pillar[5]arene, bovine serum albumin, and methyl orange) biosupramolecular system as a potential drug delivery system. We estimated the cytotoxic activity and transfection ability of pillar[5]arene derivatives and investigated the effect of the nature of macrocycle functions (L-phenylalanine, glycine, L-alanine) on the native conformation of serum albumin in a three-component system. NMR, UV-vis, fluorescence, CD spectroscopy, DLS, and molecular docking studies were performed in order to confirm the structure and possible pillar[5]arene/bovine serum albumin/methyl orange interactions occurring during the association process. Results indicate that pillar[5]arene with L-phenylalanine fragments retains the native form of BSA to the maximum extent and forms more stable associates.

Complexation study of syringaldehyde complexed with serum albumin

As a major flavonoid polyphenolic compound in the stem of Hibiscus taiwanensis, syringaldehyde (SA) has numerous pharmacological effects. Nevertheless, owing to its less in-depth study, its application is limited. Within this work, the interactions between serum albumin and SA were elucidated by multispectral studies. The results of ultraviolet/visible absorption spectroscopy suggest that the conformation of serum albumin can be altered by binding with SA. Fluorescence spectroscopy indicates that SA forms complexes with serum albumin, quenching its fluorescence. This suggests that the fluorescent residues of serum albumin are situated at or near the binding site. Additionally, FT-IR results confirm that SA alters the secondary structure of BSA, specifically affecting the positions of both amide I and amide II bands. Via the computational biology analyses, it was confirmed that SA binds at the active site of serum albumin and nine residues form hydrophobic interactions. In addition, the cytotoxicity of SA to BRL-3A cells was also studied, and SA had almost no toxicity to the growth of BRL-3A cells. The complex has a higher α-amylase inhibition capacity than SA alone. To sum up, this work reveals that the interaction of SA with BSA induces a conformational alteration in BSA. It also proved that SA inhibits α-amylase more significantly and has great potential in hypoglycemia.

Co-Delivery of Metabolic Modulators Leads to Simultaneous Lactate Metabolism Inhibition And Intracellular Acidification for Synergistic Cancer Therapy.

Simultaneous lactate metabolism inhibition and intracellular acidification (LIIA) is a promising approach for inducing tumor regression by depleting ATP. However, given the limited efficacy of individual metabolic modulators, a combination of various modulators is required for highly efficient LIIA. Herein, a co-delivery system that combines lactate transporter inhibitor, glucose oxidase, and O2 -evolving nanoparticles is proposed. As a vehicle, a facile room-temperature synthetic method for large-pore mesoporous silica nanoparticles (L-MSNs) is developed. O2 -evolving nanoparticles are then conjugated onto L-MSNs, followed by immobilizing the lactate transporter inhibitor and glucose oxidase inside the pores of L-MSNs. To load the lactate transporter inhibitor, which is too small to be directly loaded into the large pores, it is encapsulated in albumin by controlling the albumin conformation before being loaded into L-MSNs. Notably, inhibiting lactate efflux shifts the glucose consumption mechanism from lactate metabolism to glucose oxidase reaction, which eliminates glucose and produces acid. This leads to synergistic LIIA and subsequent ATP depletion in cancer cells. Consequently, L-MSN-based co-delivery of modulators for LIIA shows high anticancer efficacy in several mouse tumor models without toxicity in normal tissues. This study provides new insights into co-delivery of small-molecule drugs, proteins, and nanoparticles for synergistic metabolic modulation in tumors. This article is protected by copyright. All rights reserved.

The Role of Correcting Structural and Functional Albumin Properties in Ascites Control in Decompensated Cirrhotic Patients

Аim: to study the structural and functional characteristics of albumin in patients with decompensated cirrhosis, their relationship with ascites; to identify the relationship between improvement in albumin characteristics and regression of ascites.Materials and methods. Fifty patients with decompensated liver cirrhosis and ascites were divided into groups. The first group received standard treatment for cirrhosis, the second — standard treatment and replacement therapy with 20 % human albumin solution at a dose of 200 mL per week for 3 months.Results. The value of the native conformation of albumin and the functional parameters of albumin were significantly lower than in the group of healthy individuals (p < 0.001). With the severity of ascites, the native conformation index (DR), which characterizes the structural usefulness of the albumin molecule, decreased. Median DR for ascites stage I (IAC) was –1.69, II grade — –2.28, III grade — –2.42 (p < 0.05). Replacement therapy with albumin allowed to achieve regression of ascites in 48.4 % of patients, compared with 7.1 % in the standard treatment group. Along with clinical improvement, restoration of albumin structural and functional properties was observed in the albumin group. The mean serum albumin level at which ascites remained in remission for 3 months was 42.11 g/L (p < 0.001).Conclusions and discussion. The structural and functional characteristics of albumin were impaired in patients with decompensated cirrhosis and ascites. The severity of changes in the structural and functional properties of albumin depended on the severity of ascites. The regression of ascites was accompanied by the restoration of the functional and structural usefulness of albumin against the backdrop of albumin replacement therapy. The criterion for stopping transfusion therapy with albumin can be the achievement of a serum albumin level of 42.11 ± 7.04 g/L, DR — 1.05, BE — 73.51 %, RTQ — 75.10 %, DTE — 72.71 %.

Conformational variation of site specific glycated albumin: A Molecular dynamics approach

Human serum albumin (HSA) is a major cargo protein, which undergoes glycation in hyperglycaemic conditions and results in impaired function. In physiological conditions, HSA plays a crucial role in pharmacological activities such as drug transport or delivery through its binding capacity and also by its enzymatic activity, which enables the translation of pro-drugs into active drugs. In this study, the impact of the methylglyoxal-mediated glycation on dynamic behaviour of inter-domain motion, Cys34 reactivity, binding site residual interaction and secondary structure transition were investigated through molecular dynamics simulation. The alteration in inter-domain motion reflects the effect of glycation-mediated changes on the structural conformation of albumin. The binding site residue interactions and volume analysis revealed the impact of glycation on the geometry of the binding site. We also found the correlation of Cys34 reactivity with increase of turns in the region between Ia-h4 and Ia-h5. The rise in turn formation in that region keeps Tyr84 farther away from Cys34 which could lead to higher Cys34 reactivity. In parallel, significant alterations in alpha helical content of helices in the binding sites were observed. These structural and conformational changes in glycated albumin could be the causative agents for functional impairment which leads to diabetic complications.

Comparative investigation on interaction mechanism and native conformation of human serum albumin with organometallic iridium(III) complexes via spectroscopic and electrochemical approaches

Organometallic iridium(III) complexes, as high-efficient phototherapic drugs for cancer therapy and tumor treatment, have attracted widespread interest in diverse areas. To further clarify the biological functions of iridium(III) complexes, the interaction mechanism and native conformation of human serum albumin (HSA) affected by three organometallic iridium(III) complexes containing curcuminoid ligands were systematically and comparably investigated via various spectroscopic and electrochemical approaches. The results revealed that three iridium(III) complexes reacted with HSA tightly at its Sudlow's site I under the binding forces of van der Waals interaction, protonation, and hydrogen bond, leading to the hypochromic effect in the absorption spectrum of HSA and the static quenching in the intrinsic fluorescence of HSA. Three iridium(III) complexes disturbed the native conformation of HSA by reducing its α-helical content, finally reducing the melting temperature and the thermal stability of HSA. In comparison, the iridium(III) complex containing curcuminoid ligand with bigger spatial steric-hindrance effect and stronger chemical polarity was prone to binding with HSA more tightly and subsequently affecting its native conformation and biological function more prominently. This research finding reveals the interaction mechanisms of organometallic iridium(III) complexes with HSA and evaluates the function of curcuminoid ligands during their binding interactions, which pays the way for the targeted design and the potential application of novel iridium(III) complexes in biological fields.

Study of the effect of accelerated electrons on the structural characteristics of the bovine serum albumin using liquid chromatography-mass spectrometry and high-resolution tandem mass spectrometry

A method for quantification of the dose effect of ionizing radiation on the structural characteristics of bovine serum albumin (BSA) in aqueous solution through identification of unique peptides of protein domain structures using high-resolution liquid chromatography-mass spectrometry is proposed. BSA with the initial concentration of 500 mg/liter in a physiological solution was exposed to irradiation at a dose rate of 18. 5 Gy/sec using an accelerated electron beam with the maximum energy of 1 MeV at an average beam current of 1 uA. The absorbed dose in the sample volume was estimated using a Fricke (ferrous sulphate) dosimeter. After irradiation of BSA solution at 0.3, 0.6,1.8, and 20 kGy we analyzed the structural integrity of the protein native form and then quantified the content. For this, masses more than 30 kDa were removed using centrifugation. Then BSA was subjected to enzymatic hydrolysis with the addition of trypsin solution, and the resulting peptides with a mass of more than 10 kDa were repeatedly removed. The resultant samples were then examined using liquid chromatography mass spectrometry (LC-MS) and high-resolution tandem mass spectrometry (HRMS-MS/MS). The content of intact protein molecules was assessed by determining the concentrations of unique peptides corresponding to each of the three domains into which the amino acid sequence of BSA was divided. Using the developed methodology, a change in the natural conformation of bovine serum albumin (denaturation) in water samples induced by ionizing radiation at a dose ranging from 0.3 to 20 kGy was revealed on average in 71% of protein molecules exposed to doses up to 1 kGy in 79% of molecules exposed to doses of 4 kGy and in 99 % to 100% of molecules exposed to doses of 8 and 20 kGy.

Effect of amphiphilic phosphorous dendrons on the conformation, secondary structure, and zeta potential of albumin and thrombin

Effect of amphiphilic phosphorous dendrons on the conformation, secondary structure, and zeta potential of albumin and thrombin

The Effect of Nanostructured Titanium Surface on Protein Adsorption

The amount and conformation of bovine serum albumin upon adsorption on titanium (Ti) surfaces containing nanotubes with different pore sizes were investigated. Nanotubes were created on the surfaces via anodization. Protein adsorption behavior on anodized surfaces were compared with the adsorption behavior on smooth and sanded Ti surfaces. The conformational changes in surface adsorbed proteins were evaluated using the second derivative and curve fitting methods applied to the Fourier transform infrared spectra of the surfaces. Results showed that the amount of protein adsorbed on the surfaces increased significantly with increasing surface roughness and a significant change in the conformation of the adsorbed protein occurred on every surface albeit in a different fashion. When anodized samples were considered, it was observed that the changes in the secondary structure seemed to be correlated with to the pore size of the nanotubes rather than the surface roughness.

Structure and Functions of Human Serum Albumin in Normal Conditions and in Patients with Liver Cirrhosis

The aim: to highlight the main points of albumin synthesis, posttranslational modifications and functions in normal conditions and in patients with liver cirrhosis.Key points. Albumin is the most abundant protein in blood plasma. Along with oncotic properties, albumin performs transport, antioxidant, immunomodulatory and endothelioprotective functions. Serum albumin in patient with liver cirrhosis undergoes modifications, leading to functional impairment. Human serum albumin is a compaund of human mercaptalbumin with cysteine residues having a reducing ability, and oxidized human non-mercaptalbumin. The proportion of irreversibly oxidized non-mercaptalbumin-2 with impaired functional activity increases in liver cirrhosis.Conclusion. The conformational structure of the albumin molecule plays an important role in maintaining its non-oncotic functions. Non-oncotic functions depend on albumin conformation. Further investigation of albumin conformation and albumin functions in patients with hepatic insufficiency can serve as an additional criterion for assessing the severity of cirrhosis and predictor of complications may become an additional criterion to new clinical applications and treatment strategies of liver failure.

Nanoplastics alter the conformation and activity of human serum albumin

Nanoplastics finds its presence in most of the consumer products. Their chance of coming in contact with human cells and components is rampant. This study focuses on the interaction of polystyrene nanoplastics (PSNPs) with human serum albumin (HSA), ultimately causing structural and functional properties of the protein. Fluorescence and UV–Visible spectroscopic studies reported that PSNPs form a spontaneous ground-state complex with HSA, by hydrogen bonding, van der waal's, and hydrophobic force of attraction. This causes changes in the environment around major aromatic amino acids, especially tryptophan-214, which has a strong affinity with PSNPs. Further docking analysis confirmed hydrophobic interactions between PSNPs and aromatic amino acids in subdomain IIA of HSA. A shift in amide bands in HSA, as determined by FTIR analysis confirmed the disturbances in its secondary structure followed by reordering which will lead to the unfolding of HSA. Besides, PSNPs reduce the esterase activity of HSA by competitive inhibition. This molecular-level information such as binding energy, binding site, binding forces, reversible or irreversible binding, and structural changes of protein will shed light on the extent of toxicity in humans. This study will emphasize the urgent need for regulation of the use of nanoplastics (NPs) in consumer products, as well as the need for more research to determine the fate of NPs in the biological system.