Review: Roles of human serum albumin in prediction, diagnoses and treatment of COVID-19

Preserved structure and function of human serum albumin self-folded in the oxidative cytoplasm of Escherichia coli

Human serum albumin (HSA), a polypeptide featuring 17 disulfide bonds, acts as a crucial transport protein in human blood plasma. Its extended circulation half-life, mediated by FcRn (neonatal Fc receptor)-facilitated recycling, positions HSA as an excellent carrier for long-acting drug delivery. However, the conventional method of obtaining HSA from human blood faces limitations due to availability and potential contamination risks, such as blood-borne diseases. This study introduced SHuffle, an oxidative Escherichia coli (E. coli) expression system, for the production of recombinant HSA (rHSA) that spontaneously self-folds into its native conformation. This system ensures precise disulfide bond formation and correct folding of cysteine-rich rHSA, eliminating the need for chaperone co-expression or domain fusion of a folding enhancer. The purified rHSA underwent thorough physicochemical characterization, including mass spectrometry, circular dichroism spectroscopy, intrinsic fluorescence spectroscopy, esterase-like activity assay, and size exclusion chromatography, to assess critical quality attributes. Importantly, rHSA maintained native binding affinity to FcRn and the albumin-binding domain. Collectively, our analyses demonstrated a high comparability between rHSA and plasma-derived HSA. The expression of rHSA in E. coli with an oxidizing cytosol provides a secure and cost-effective approach, enhancing the potential of rHSA for diverse medical applications.

Interaction studies of cannabidiol with human serum albumin by surface plasmon resonance, spectroscopy, and molecular docking

The binding interaction of cannabidiol (CBD) and human serum albumin (HSA) under physiological blood pH conditions (pH 7.4) was conducted by surface plasmon resonance (SPR), fluorescence spectroscopy, UV-Visible spectrophotometry, and molecular docking. The responses from SPR measurement increased with the increase in CBD concentration until equilibrium was reached at the equilibrium dissociation constant (KD) of 9.8 × 10-4 M. The results from fluorescence and UV-Visible spectroscopy showed that CBD bound to HSA at one site in a spontaneous manner to form protein-CBD complexes. The quenching process involved both static and dynamic mechanisms while the static mechanism contributed predominantly to the binding between CBD and albumin. The binding constants estimated from the fluorescence studies were from 0.16 × 103 to 8.10 × 103 M-1, which were calculated at different temperature conditions using Stern-Volmer plots. The thermodynamic parameters demonstrated that the binding interaction was a spontaneous reaction as Gibbs free energy had negative values (ΔG = -12.57 to -23.20 kJ.mol-1). Positive ΔH and ΔS values (ΔH = 2.46 × 105 J.mol-1 and ΔS = 869.81 J.mol-1K-1) indicated that the hydrophobic force was the major binding interaction. Finally, confirmation of the type and extent of interaction was provided using UV-spectroscopy and molecular docking studies. The outcomes of this study are expected to serve as a platform to conduct future studies on binding interactions and toxicological research of CBD.Communicated by Ramaswamy H. Sarma.

Kinetics of Human Serum Albumin Adsorption on Polycation Functionalized Silica

The adsorption kinetics of human serum albumin (HSA) on bare and poly-L-arginine (PARG)-modified silica substrates were investigated using reflectometry and atomic force microscopy (AFM). Measurements were carried out at various pHs, flow rates and albumin concentrations in the 10 and 150 mM NaCl solutions. The mass transfer rate constants and the maximum protein coverages were determined for the bare silica at pH 4.0 and theoretically interpreted in terms of the hybrid random sequential adsorption model. These results were used as reference data for the analysis of adsorption kinetics at larger pHs. It was shown that the adsorption on bare silica rapidly decreased with pH and became negligible at pH 7.4. The albumin adsorption on PARG-functionalized silica showed an opposite trend, i.e., it was negligible at pH 4 and attained maximum values at pH 7.4 and 150 mM NaCl, the conditions corresponding to the blood serum environment. These results were interpreted as the evidence of a significant role of electrostatic interactions in the albumin adsorption on the bare and PARG-modified silica. It was also argued that our results can serve as useful reference data enabling a proper interpretation of protein adsorption on substrates functionalized by polyelectrolytes.

Combined Serum Albumin and Left Ventricular Ejection Fraction Predict All-Cause Death in Patients with Stable Coronary Artery Disease

Objective

To explore the feasibility of serum albumin (Alb) and left ventricular ejection fraction (LVEF) in predicting all-cause death (ACD) in patients with stable coronary artery disease (SCAD).

Methods

Patients with SCAD were divided into 4 groups according to their Alb and LVEF levels: Group A: Alb ≤4 g/dL and LVEF > 50%; Group B: Alb ≤4 g/dL and LVEF ≤50%; Group C: Alb >4 g/dL and LVEF ≤50%; Group D: Alb >4 g/dL and LVEF >50%. The K-M curve and log-rank test were used to compare ACD among the four groups over three years. Receiver operating characteristic (ROC) curves were used to compare the efficacy of predicting ACD among the combination of Alb and LVEF and either Alb or LVEF alone. Cox regression analysis identified the influencing factors of ACD in patients with SCAD and detected the correlation between Alb and LVEF.

Results

ACD occurred in 18 (8.9%) of 203 patients with SCAD, with an average follow-up of 26.53 ± 14.34 months. In the Kaplan‒Meier analysis, the risk of ACD in the four groups ranged from high to low: Group B (17.6%) > Group A (26.7%) > Group D (0.9%) > Group C (0%, P < 0.001). The ROC curve showed that the combination of Alb and LVEF (AUC = 0.888) had better predictive value for ACD than either Alb (AUC = 0.879) or LVEF alone (AUC = 0.651), P < 0.001. Multivariate Cox regression analysis showed that Alb ≤4 g/dL predicted ACD events after adjusting for baseline (HR: 12.16, 95% CI: 1.57 to 94.41; P=0.017) and treatment (HR: 19.36, 95% CI: 2.53-147.78, P=0.004). Alb was positively correlated with LVEF (r = 0.22, P=0.002).

Conclusions

Alb combined with LVEF is more effective than a single index in predicting ACD in SCAD and could be used as a new model to judge the prognosis of SCAD.

Epidemiology, clinical features and outcomes of hospitalized patients with COVID-19 by vaccination status: a multicenter historical cohort study

INTRODUCTION

COVID-19 disease resulted in over six million deaths worldwide. Although vaccines against SARS-CoV-2 demonstrated efficacy, breakthrough infections became increasingly common. There is still a lack of data regarding the severity and outcomes of COVID-19 among vaccinated compared to unvaccinated individuals.

METHODS

This was a historical cohort study of adult COVID-19 patients hospitalized in five Ascension hospitals in southeast Michigan. Electronic medical records were reviewed. Vaccine information was collected from the Michigan Care Improvement Registry. Data were analyzed using Student's t-test, analysis of variance, the chi-squared test, the Mann-Whitney and Kruskal-Wallis tests, and multivariable logistic regression.

RESULTS

Of 341 patients, the mean age was 57.9 ± 18.3 years, 54.8% (187/341) were female, and 48.7% (166/341) were black/African American. Most patients were unvaccinated, 65.7%, 8.5%, and 25.8% receiving one dose or at least two doses, respectively. Unvaccinated patients were younger than fully vaccinated (p = 0.001) and were more likely to be black/African American (p = 0.002). Fully vaccinated patients were 5.3 times less likely to have severe/critical disease (WHO classification) than unvaccinated patients (p < 0.001) after controlling for age, BMI, race, home steroid use, and serum albumin levels on admission. The case fatality rate in fully vaccinated patients was 3.4% compared to 17.9% in unvaccinated patients (p = 0.003). Unvaccinated patients also had higher rates of complications.

CONCLUSIONS

Patients who were unvaccinated or partially vaccinated had more in-hospital complications, severe disease, and death as compared to fully vaccinated patients. Factors associated with severe COVID-19 disease included advanced age, obesity, low serum albumin, and home steroid use.

Study on the toxicity prediction model ofacetolactate synthase inhibitor herbicides based on human serum albumin and superoxide dismutase binding information

Toxicity significantly influences the successful development of drugs. Based on the toxicity prediction method (carrier protein binding information-toxicity relationship) previously established by the our group, this paper introduces information on the interaction between pesticides and environmental markers (SOD) into the model for the first time, so that the toxicity prediction model can not only predict the toxicity of pesticides to humans and animals, but also predict the toxicity of pesticides to the environment. Firstly, the interaction of acetolactate synthase inhibitor herbicides (ALS inhibitor herbicides) with human serum albumin (HSA) and superoxide dismutase (SOD) was investigated systematically from theory combined with experiments by spectroscopy methods and molecular docking, and important fluorescence parameters were obtained. Then, the fluorescence parameters, pesticides acute toxicity LD50 and structural splitting information were used to construct predictive modeling of ALS inhibitor herbicides based on the carrier protein binding information (R2 = 0.977) and the predictive modeling of drug acute toxicity based on carrier protein binding information and conformational relationship (R2 = 0.991), which had effectively predicted pesticides toxicity in humans and animals. To predict potential environmental toxicity, the predictive modeling of drug acute toxicity based on superoxide dismutase binding information was established (R2 = 0.883) by ALS inhibitor herbicides-SOD binding information, which has a good predictive ability in the potential toxicity of pesticides to the environment. This study lays the foundation for developing low toxicity pesticides.

Oxidative stress induced conformational changes of human serum albumin

Oxidative stress, generated by reactive oxygen species (ROS), is responsible for the loss of structure and functionality of proteins and is associated with several aging-related diseases. Here, we report an in vitro study to gauge the effect of ROS on the structural rearrangement of human serum albumin (HSA), a plasma protein, through metal-catalyzed oxidation (MCO) at physiological temperature through various biophysical techniques like UV-vis absorption, circular dichroism (CD), differential scanning calorimetry (DSC), MALDI-TOF, FTIR, and Raman spectroscopy. The UV-vis spectra of oxidized HSA show an early blueshift, signifying the unfolding of the protein because of ROS followed by the broadening of the absorption peak at a longer time. The DSC data corroborate the observation, revealing an exothermic transition for the oxidized sample at a longer time, suggesting in situ aggregation. The CD and FTIR spectra indicate the associated secondary structural changes occurring with time, depicting the variation of the helical content of HSA. The amide-III analysis of Raman data also complements the structural changes, and MALDI-TOF data show the mass distribution with time. Overall, this work might help determine the effect of oxidation on the biological activity of serum albumin as it can impact the physiological properties of HSA.

Predictive value of serum albumin levels on cancer survival: a prospective cohort study

Background

Serum albumin levels and cancer mortality are closely related, yet large-sample studies encompassing a broad spectrum of cancer types are lacking.

Methods

This study encompassed patients diagnosed with cancer across the continuous 10 cycles of NHANES surveys from 1999 to 2018. The study population was stratified into two groups based on median albumin levels (≤ 4.2g/dL and > 4.2 g/dL) or cancer aggressiveness (well-survived cancers and poorly-survived cancers). Survival rates were estimated using the Kaplan-Meier method. The Cox proportional hazards model was employed to evaluate the association between serum albumin levels and cancer mortality. Restricted cubic spline (RCS) analysis was conducted to assess the nonlinear relationship between serum albumin levels and the risk of cancer mortality.

Results

Kaplan-Meier curves demonstrated that patients with albumin levels ≤ 4.2 g/dL exhibited lower survival rates compared to those with levels > 4.2 g/dL, irrespective of cancer aggressiveness. Following adjustment for confounders, decreased albumin levels were associated with an elevated risk of cancer mortality across all groups [all cancers, HR (95%CI) = 2.03(1.73, 2.37); well survived cancers, HR (95%CI) = 1.78(1.38, 2.32); and poorly survived cancers, HR (95%CI) = 1.99(1.64, 2.42)]. RCS analyses revealed a stable nonlinear negative association between albumin levels and cancer mortality in all groups, regardless of confounder adjustment.

Conclusion

Low serum albumin levels predict higher cancer mortality. Furthermore, a nonlinear negative association was observed between serum albumin levels and the risk of cancer mortality.

Decoding acute myocarditis in patients with COVID-19: Early detection through machine learning and hematological indices

During the persistent COVID-19 pandemic, the swift progression of acute myocarditis has emerged as a profound concern due to its augmented mortality, underscoring the urgency of prompt diagnosis. This study analyzed blood samples from 5,230 COVID-19 individuals, identifying key blood and myocardial markers that illuminate the relationship between COVID-19 severity and myocarditis. A predictive model, applying Bayesian and random forest methodologies, was constructed for myocarditis' early identification, unveiling a balanced gender distribution in myocarditis cases contrary to a male predominance in COVID-19 occurrences. Particularly, older men exhibited heightened vulnerability to severe COVID-19 strains. The analysis revealed myocarditis was notably prevalent in younger demographics, and two subvariants COVID-19 progression paths were identified, characterized by symptom intensity and specific blood indicators. The enhanced myocardial marker model displayed remarkable diagnostic accuracy, advocating its valuable application in future myocarditis detection and treatment strategies amidst the COVID-19 crisis.

Bioengineered cellulosic paper micro-device for serum albumin detection in clinical range

Chronic Kidney Disease (CKD) is becoming one of the major causes of morbidity and mortalities in 21st century. We have developed a bioengineered cellulosic paper device for the quantification of albumin (ALB) in physiological samples. The paper surface was activated and antibodies specific to target biomarker was immobilized on engineered paper surface. Every step after modification was characterized by FTIR, XPS, SPM and optical analysis. Further, the device model was designed using CAD file, and a 3-D cascade device was fabricated with in-built constant light source to provide proper and controlled environment for in-situ image analysis. After adding the sample on the bioengineered paper, the antigen-antibody reaction takes place, after that addition of dye results in change of color from yellow to blueish-green within 40 s. An optical method was employed for the analysis of the images by recognizing the specific area and the color intensity. Additionally, the immunosensor specificity was evaluated on number of molecules that are usually found in the serum sample. The linear dynamic range of the developed immunosensor has been reported to be 1-60 mg/mL, covering the normal as well as clinical range of ALB in physiological samples with a detection limit of 0.049(±0.002) mg/mL. With good precision and recovery, the device was able to successfully determine the ALB concentrations in serum sample. The developed device has simple and user-friendly interface and it may also help diagnosing CKD in personalized settings.

Investigating the effect of pH on the interaction of cypermethrin with human serum albumin: Insights from spectroscopic and molecular dynamics simulation studies

To efficiently combat the negative consequences of the utilization of pesticides and hazardous substances with biomolecules, it is crucial to comprehend the features of the corresponding compounds. In this study, interactions between cypermethrin (CYP) and HSA at neutral and acidic pH were investigated using a set of spectroscopic and computational tools, such as UV/VIS's absorption spectroscopy, fluorescence, Fourier-transform infrared (FTIR) spectroscopy, molecular docking, and molecular dynamics. Furthermore, the effect of CYP on the HSA thermal stability was investigated. The increase in the CYP concentration at acidic and neutral pH resulted in static HSA fluorescence quenching. In the interaction between HSA and CYP at both pH, increasing the temperature led to a decrease in the Stern-Volmer quenching constant and the binding constant. We also revealed that with increasing CYP concentration, the melting temperature of HSA increases at both pH values.

Interactions of ferulic acid and ferulic acid methyl ester with endogenous proteins: Determination using the multi-methods

Ferulic acid (FA) and ferulic acid methyl ester (FAM) are important phenolic compounds in Baijiu. In this study, the interaction of FA and FAM with human serum albumin (HSA) and lysozyme (LZM) was investigated using multispectral methods and molecular dynamics simulation. FA and FAM could interact with HSA and LZM, changing the conformation and hydrophilicity of the protein. The quenching mechanisms of FA-HSA, FA-LZM, FAM-HSA, and FAM-LZM were all static-quenching. In the FA-HSA, FAM-HSA, and FA-LZM systems, the interaction forces were mainly hydrophobic interactions and hydrogen bonding. In the FAM-LZM system, the interaction forces were mainly hydrophobic interactions, hydrogen bonding, and van der Waals force. Common metal ions such as K+, Ca2+, Cu2+, Mg2+, and Mn2+ could affect the binding ability of FA and FAM to HSA and LZM. Moreover, FA and FAM could increase the stability of HSA and LZM, and the protein bound to FA/FAM was more stable than the free protein. FA and FAM had varying degrees of impact on the physiological activities of HSA and LZM. This study provides relevant information on the interactions and metabolic mechanisms of FA and its derivatives with endogenous proteins.

Human Serum Albumin-Platinum(II) Agent Nanoparticles Inhibit Tumor Growth Through Multimodal Action Against the Tumor Microenvironment

To overcome the limitations of traditional platinum (Pt)-based drugs and further improve the targeting ability and therapeutic efficacy in vivo, we proposed to design a human serum albumin (HSA)-Pt agent complex nanoparticle (NP) for cancer treatment by multimodal action against the tumor microenvironment. We not only synthesized a series of Pt(II) di-2-pyridone thiosemicarbazone compounds and obtained a Pt(II) agent [Pt(Dp44mT)Cl] with significant anticancer activity but also successfully constructed a novel HSA-Pt(Dp44mT) complex nanoparticle delivery system. The structure of the HSA-Pt(Dp44mT) complex revealed that Pt(Dp44mT)Cl binds to the IIA subdomain of HSA and coordinates with His-242. The HSA-His242-Pt-Dp44mT NPs had an obvious effect on the inhibition of tumor growth, which was superior to that of Dp44mT and Pt(Dp44mT)Cl, and they had almost no toxicity. In addition, the HSA-His242-Pt-Dp44mT NPs were found to kill cancer cells by inducing apoptosis, autophagy, and inhibiting angiogenesis.

Comparing the interactions of nitrendipine with lysozyme or human serum albumin and the effects of vitamin C and naringin on these interactions by spectroscopy and molecular docking methods

The interactions between drugs and proteins play a pivotal role in determining the pharmacological effects and disposition of drugs within the human body. This study focuses on exploring the interaction between nitrendipine and lysozyme/human serum albumin. Spectroscopic analysis indicated a compound static quenching, indicative of the formation of stable complexes between the drug and proteins. The addition of vitamin C or naringin resulted in a decrease of the binding constant between nitrendipine and lysozyme/human serum albumin. The presence of these compounds may disrupt the interactions between the drug and proteins, potentially leading to an increased concentration of free nitrendipine in the bloodstream. Nitrendipine binds more easily to human serum albumin at 310 K, and human serum albumin has an average binding site ratio with nitrendipine approximately 0.1 higher than that with lysozyme. Vitamin C has a greater impact on the binding constant of nitrendipine to human serum albumin and lysozyme. Compared to the binary system of proteins with the drug, the ternary system with the addition of vitamin C at 310 K reduces the binding constants of lysozyme and human serum albumin by 85%. In conclusion, this study explores the significance of considering drug-protein interactions in understanding drug behavior and potential drug-food interactions.

Multi-cavity molecular descriptor interconnections: Enhanced protocol for prediction of serum albumin drug binding

The role of human serum albumin (HSA) in the transport of molecules predicates its involvement in the determination of drug distribution and metabolism. Optimization of ADME properties are analogous to HSA binding thus this is imperative to the drug discovery process. Currently, various in silico predictive tools exist to complement the drug discovery process, however, the prediction of possible ligand-binding sites on HSA has posed several challenges. Herein, we present a strong and deeper-than-surface case for the prediction of HSA-ligand binding sites using multi-cavity molecular descriptors by exploiting all experimentally available and crystallized HSA-bound drugs. Unlike previously proposed models found in literature, we established an in-depth correlation between the physicochemical properties of available crystallized HSA-bound drugs and different HSA binding site characteristics to precisely predict the binding sites of investigational molecules. Molecular descriptors such as the number of hydrogen bond donors (nHD), number of heteroatoms (nHet), topological polar surface area (TPSA), molecular weight (MW), and distribution coefficient (LogD) were correlated against HSA binding site characteristics, including hydrophobicity, hydrophilicity, enclosure, exposure, contact, site volume, and donor/acceptor ratio. Molecular descriptors nHD, TPSA, LogD, nHet, and MW were found to possess the most inherent capacities providing baseline information for the prediction of serum albumin binding site. We believe that these associations may form the bedrock for establishing a solid correlation between the physicochemical properties and Albumin binding site architecture. Information presented in this report would serve as critical in provisions of rational drug designing as well as drug delivery, bioavailability, and pharmacokinetics.

Post-imprinting modification of molecularly imprinted polymer for proteins detection: A review

Inspired by protein post-translational modification (PTM), post-imprinting modification (PIM) has been proposed and developed to prepare novel molecularly imprinted polymers (MIPs), which are similar to functionalized biosynthetic proteins. The PIM involves site-directed modifications in the imprinted cavity of the MIP, such as introducing high-affinity binding sites and introducing fluorescent signal molecules. This modification makes the MIP further functionalized and improves the shortcomings of general molecular imprinting, such as single function, low selectivity, low sensitivity, and inability to fully restore the complex function of natural antibodies. This paper describes the characteristics of PIM strategies, reviews the latest research progress in the recognition and detection of protein biomarkers such as lysozyme, prostate-specific antigen, alpha-fetoprotein, human serum albumin, and peptides, and further discusses the importance, main challenges, and development prospects of PIM. The PIM technology has the potential to develop a new generation of biomimetic recognition materials beyond natural antibodies. It can be used in bioanalysis and other multitudinous fields for its unique features in molecule recognition.

The effect of nutritional biochemical indexes on the hospitalization outcome of COVID-19

Aims to investigate the relationship between nutritional biochemical indexes and hospitalization outcomes of COVID-19 patients, 132 continuous patients with COVID-19 from December 2022 to January 2023 in Lishui hospital were retrospectively analyzed, and the nutritional biochemical indexes in peripheral blood, such as total protein, albumin, calcium, phosphorus, and magnesium, were detected. Meanwhile, the levels of several cytokines and PBMC subtypes (CD4, CD3, CD8, NK and B cells) were detected too. The Spearman correlation analysis, one-way ANOVA and multivariate logit regression were conducted. Results suggested that the levels of total protein and albumin were significantly decreased in patients with poor outcomes, and the levels of calcium, phosphorus, and magnesium were significantly correlated with hospitalization outcomes. COVID-19 patients with diabetes had higher levels of IL-6 and IFN-γ than those patients without diabetes. The levels of IL-2, IFN-γ, IL-6 and Il-10 in the dead patients were significantly higher than those in the recovery and worse patients. Total protein and albumin were significantly positively correlated with levels of NK and B, CD4, CD8, CD3 lymphocytes. The levels of CD4, CD8 and CD3 lymphocytes were significantly decreased in dead patients than other patients. Multivariate logit regression analysis suggests that lymphocyte number, albumin and IL-6 are independent risk factors to evaluate the hospitalization outcome. In summary, nutritional biochemical indexes were significantly corelated with cytokines and PBMC subsets, and had an impact on the severity of COVID-19 patients. Improvement of low protein malnutrition is broad-spectrum and basic strategy to improve the hospitalization outcome of COVID-19.

Unveiling the molecular interactions between alkyl imidazolium ionic liquids and human serum albumin: Implications for toxicological significance

Alkyl imidazolium-based ionic liquids (ILs) are promising for diverse industrial applications; however, their growing prevalence has raised concerns regarding human exposure and potential health implications. A critical aspect to be clarified to address the adverse health effects associated with ILs exposure is their binding mode to human serum albumin (HSA). In this study, we delved into the binding interactions between three alkyl imidazolium ILs (1-hexyl-3-methyl-imidazolium (C6[MIM]), 1-ethyl-3-methyl-imidazolium chloride (C8[MIM]) and 1-decyl-3-methyl-imidazolium (C10[MIM]) and human serum albumins (HSAs) using a comprehensive approach encompassing molecular docking and multi-spectroscopy (UV-visible, Fluorescence, Circular Dichroism, FTIR). Furthermore, for the first time, we developed an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach time to quantify plasma protein binding rates. Our results revealed that the ILs primarily bind to the hydrophobic cavity of HSA through hydrogen bonding and van der Waals forces, forming stable complexes via static quenching. This affected HSA's secondary structure, reducing α-helical content, particularly around specific residues. Equilibrium dialysis and ultrafiltration coupled with UPLC-MS/MS analysis showed modest plasma protein binding rates (17.84%-31.85%) for the three ILs, with no significant influence from alkyl chain effects or concentration relationship. Lower plasma protein binding rates can affect bioavailability and distribution of ILs, potentially influencing their toxicity. These findings provide critical insights into the potential toxicological implications at the molecular level, thereby contributing to continuous efforts to evaluate the risk profiles and ensure the safe utilization of these compounds.

Building Surfaces with Controlled Site-Density of Anchored Human Serum Albumin

Stable and uniform layers of protein molecules at the surface are important to build passive devices as well as active constructs for smart biointerfaces for a large number of biomedical applications. In this context, a strategy to build-up surfaces able to anchor protein molecules on specific and controlled surface sites has been developed. Human serum albumin (HSA) has been chosen as a model protein due to its important antithrombogenic properties and its features in cell response highly valuable for in vivo devices. Uniform self-assembled monolayers of 2,2':6'2″-terpyridines (SAM), whose sites were further employed to chelate copper and iron ions, forming SAM-Cu(II) and SAM-Fe(II) complexes, have been developed. The effect of two metal cations on the physicochemical features of SAM, including thickness, Young's modulus, and tip-monolayer adhesion factors, has been investigated. Protein adsorption at different concentrations showed that the copper ion-templated surfaces exhibit highly specific mass uptake, kinetic behavior, and recognition and anchoring of HSA molecules owing to the coordination sphere of the different cations. The results pave the way to the development of a more general strategy to obtain ordered and density-tuned arrays of specific metal cations, which in turn would drive the anchoring of precise proteins for different biological functions.

Semi-synthetic human albumin isoforms: Production, structure, binding capacities and influence on a routine laboratory test

Human Serum Albumin (HSA) undergoes Post-Translational-Modifications (PTMs) leading to isoforms affecting its oncotic and non-oncotic properties. HSA is comprised of several isoforms whose abundance may vary with pathologies such as diabetes, kidney and liver diseases. Studying their impact separately may help to understand their sources and potential pathogenicity and further their evaluation as biomarkers. The present study examined semi-synthetic HSA isoforms to investigate independently their structure by means of advanced mass spectrometry techniques (LC-TOF-MS and ICP-MS), influence on the HSA binding/antioxidant activities using a binding capacity test, and potential impact on albumin quantification by a routine immunoturbidimetric assay. Applying different chemical reactions to a commercial HSA solution, we obtained different solutions enriched up to 53 % of native HSA, 78 % of acetylated HSA, 71 % of cysteinylated HSA, 94 % of oxidized HSA, 58 % of nitrosylated HSA and 96 % of glycated HSA, respectively. Moreover, the semi-synthetic isoforms showed differently altered binding capacities for a panel of ligands (Cu, Cd, Au, Ds and L-T4). Furthermore, immunoturbidimetry was found to be insensitive to the presence and abundance of the different isoforms. The fully characterized semi synthetic HSA isoforms obtained should be useful to further investigate their pathogenicity and potential roles as biomarkers.

Insights into the interaction of human serum albumin with ionic liquids - Thermodynamic, spectroscopic and molecular modelling studies

Human serum albumin (HSA) effectively binds different types of low-molecular-weight compounds and thus enables their distribution in living organisms. Recently, it has been reported that the protein-ligand interactions play a crucial role in bioaccumulation processes and provide an important sorption phase, especially for ionogenic compounds. Therefore, the binding interactions of such compounds with proteins are the subject of an ongoing interest in environmental and life sciences. In this paper, the influence of some counter-ions, namely [B(CN)4]- and [C(CN)3]- on the affinity of the [IM1-12]+ towards HSA has been investigated and discussed based on experimental methods (isothermal titration calorimetry and steady-state fluorescence spectroscopy) and molecular dynamics-based computational approaches. Furthermore, the thermal stability of the resulting HSA/ligand complexes was assessed using DSC and CD spectroscopy. As an outcome of the work, it has been ascertained that the protein is able to bind simultaneously the ligands under study but in different regions of HSA. Thus, the presence in the system of [IM1-12]+ does not disturb the binding of [C(CN)3]- and [B(CN)4]-. The presented results provide important information on the presence of globular proteins and some ionogenic compounds in the distribution and bioaccumulation of ILs in the environment and living organisms.

A binuclear Cu(I)-phosphine complex as a specific HSA site I binder: synthesis, X-ray structure determination, and a comprehensive HSA interaction analysis

In this research, we present a method for synthesis and a detailed description of geometry characterization of a novel binuclear Cu(I) phosphine complex, along with analysis of its interaction with HSA using spectroscopic and simulation methods. The Cu atoms are coordinated in a tetrahedral geometry, which results in coordination by two nitrogen atoms from the N,N'-(ethane-1,2-diyl)bis(1-(pyridin-2-yl)methanimine ligand (L), a chloride, and a PPh3. The complex binding constant to HSA in a biochemical environment was determined to be ∼106, which is indicative of a strong interaction. The fluorescence of HSA is significantly quenched by binding to the complex via a static mechanism, whereas the microenvironment of the tryptophan residue remains unchanged. A spontaneous binding process was indicated by a negative value for ΔG. Thermodynamic signatures reflect the dominance of hydrophobic forces during the interaction. The site marker competitive experiment combined with docking simulation analysis revealed the closeness position of the complex binding site to warfarin location in specific ligand site I of HSA. The information generated in the present study would be valuable to understand the interaction mechanistic and pharmacological behavior of Cu(I) complexes.Communicated by Ramaswamy H. Sarma.

Binding of human serum albumin with uranyl ion at various pH: an all atom molecular dynamics study

Uranium is routinely handled in various stages of nuclear fuel cycle and its association with human serum albumin (HSA) has been reported in literature, however, their binding characteristics still remains obscure. The present study aims to understand interaction of uranium with HSA by employing all atom molecular dynamics simulation of the HSA-metal ion complex. His67, His247 and Asp249 residues constitute the major binding site of HSA, which capture the uranyl ion (UO22+). A total of six sets of initial coordinates are used for Zn2+-HSA and UO22+-HSA system at pH = 4, 7.4 and 9, respectively. Enhance sampling method, namely, well-tempered meta-dynamics (WT-MtD) is employed to study the binding and un-binding processes of UO22+ and Zn2+ ions. Potential of mean force (PMF) profiles are generated for all the six sets of complexes from the converged WT-MtD run. Various basins and barriers are observed along the (un)binding pathways. Hydrogen bond dynamics and short-range Coulomb interactions are evaluated from the equilibrium run at each basins and barriers for both the ions at all pH values. The binding of UO22+ ion with HSA is the result of the dynamical balance between UO22+-HSA and UO22+-water short range Coulomb interactions. Zn2+ ion interact more strongly than UO22+ at all pH through short range Coulomb interactions. PMF values further concludes that UO22+ cannot associate to the Zn2+ bound HSA protein but can be captured by free HSA at all pH values i.e. endosomal, alkaline and physiological pH.Communicated by Ramaswamy H. Sarma.

Computational investigation of peptidomimetics as potential inhibitors of SARS-CoV-2 spike protein

Several variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were observed since the outbreak of the global pandemic at the end of 2019. The trimeric spike glycoprotein of the SARS-CoV-2 virus is crucial for the viral access to the host cell by interacting with the human angiotensin converting enzyme 2 (ACE2). Most of the mutations take place in the receptor-binding domain (RBD) of the S1 subunit of the trimeric spike glycoprotein. In this work, we targeted both S1 and S2 subunits of the spike protein in the wild type (WT) and the Omicron variant guided by the interaction of the neutralizing monoclonal antibodies. Virtual screening of two different peptidomimetics databases, ChEMBL and ChemDiv databases, was carried out against both S1 and S2 subunits. The use of these two databases provided diversity and enhanced the chance of finding protein-protein interaction inhibitors (PPIIs). Multi-layered filtration, based on physicochemical properties and docking scores, of nearly 114,000 compounds found in the ChEMBL database and nearly 14,000 compounds in the ChemDiv database was employed. Four peptidomimetics compounds were effective against both the WT and the Omicron S1 subunit with the minimum binding free energy of -25 kcal/mol. Five peptidomimetics compounds were effective against the S2 subunit with the minimum binding free energy of -19 kcal/mol. The dynamical cross-correlation matrix insinuated that the mutations of the RBD in the Omicron variant of the SARS-CoV-2 virus altered the correlated conformational motion of the different regions of the protein.Communicated by Ramaswamy H. Sarma.

The kynurenine pathway of tryptophan metabolism: a neglected therapeutic target of COVID-19 pathophysiology and immunotherapy

SARS-CoV-2 (COVID-19) exerts profound changes in the kynurenine (Kyn) pathway (KP) of tryptophan (Trp) metabolism that may underpin its pathophysiology. The KP is the main source of the vital cellular effector NAD+ and intermediate metabolites that modulate immune and neuronal functions. Trp metabolism is the top pathway influenced by COVID-19. Sixteen studies established virus-induced activation of the KP mediated mainly by induction of indoleamine 2,3-dioxygenase (IDO1) in most affected tissues and of IDO2 in lung by the increased release of proinflammatory cytokines but could additionally involve increased flux of plasma free Trp and induction of Trp 2,3-dioxygenase (TDO) by cortisol. The major Kyn metabolite targeted by COVID-19 is kynurenic acid (KA), the Kyn metabolite with the greatest affinity for the aryl hydrocarbon receptor (AhR), which is also activated by COVID-19. AhR activation initiates two important series of events: a vicious circle involving IDO1 induction, KA accumulation and further AhR activation, and activation of poly (ADP-ribose) polymerase (PARP) leading to NAD+ depletion and cell death. The virus further deprives the host of NAD+ by inhibiting its main biosynthetic pathway from quinolinic acid, while simultaneously acquiring NAD+ by promoting its synthesis from nicotinamide in the salvage pathway. Additionally, the protective effects of sirtuin 1 are minimised by the PARP activation. KP dysfunction may also underpin the mood and neurological disorders acutely and during 'long COVID'. More studies of potential effects of vaccination therapy on the KP are required and exploration of therapeutic strategies involving modulation of the KP changes are proposed.

Large-scale and cost-effective production of recombinant human serum albumin (rHSA) in transgenic Bombyx mori cocoons

HSA is considered a versatile natural cargo carrier with multiple bio-functions and applications. However, insufficient supply of HSA has limited widespread use. Although various recombinant expression systems had been applied to produce the rHSA to overcome the limited resource, cost-effective and large scale production of rHSA remains a challenge. Herein, we provide a strategy for the large-scale and cost-effective production of rHSA in cocoons of transgenic silkworms, achieving a final 13.54 ± 1.34 g/kg of rHSA yield in cocoons. rHSA was efficiently synthesized and stable over the long-term in the cocoons at room temperature. Artificial control of silk crystal structure during silk spinning significantly facilitated rHSA extraction and purification, with 99.69 ± 0.33 % purity and a productivity of 8.06 ± 0.17 g rHSA from 1 kg cocoons. The rHSA had the same secondary structure to natural HSA, along with effective drug binding capacity, biocompatibility, and bio-safe. The rHSA was successfully evaluated as a potential substitute in serum-free cell culture. These findings suggest the silkworm bioreactor is promising for large-scale and cost-effective production of high quality rHSA to meet the increased worldwide demand.

Identification and characterization of 7-azaindole derivatives as inhibitors of the SARS-CoV-2 spike-hACE2 protein interaction

The COVID-19 pandemic, caused by SARS-CoV-2, has become a global public health crisis. The entry of SARS-CoV-2 into host cells is facilitated by the binding of its spike protein (S1-RBD) to the host receptor hACE2. Small molecule compounds targeting S1-RBD-hACE2 interaction could provide an alternative therapeutic strategy sensitive to viral mutations. In this study, we identified G7a as a hit compound that targets the S1-RBD-hACE2 interaction, using high-throughput screening in the SARS2-S pseudovirus model. To enhance the antiviral activity of G7a, we designed and synthesized a series of novel 7-azaindole derivatives that bind to the S1-RBD-hACE2 interface. Surprisingly, ASM-7 showed excellent antiviral activity and low cytotoxicity, as confirmed by pseudovirus and native virus assays. Molecular docking and molecular dynamics simulations revealed that ASM-7 could stably bind to the binding interface of S1-RBD-hACE2, forming strong non-covalent interactions with key residues. Furthermore, the binding of ASM-7 caused alterations in the structural dynamics of both S1-RBD and hACE2, resulting in a decrease in their binding affinity and ultimately impeding the viral invasion of host cells. Our findings demonstrate that ASM-7 is a promising lead compound for developing novel therapeutics against SARS-CoV-2.

The effect of novel tyrosine-modified polyethyleneimines on human albumin structure - Thermodynamic and spectroscopic study

The interaction of proteins with nanoparticle components are crucial for the evaluation of nanoparticle function, toxicity and biodistribution. Polyethyleneimines (PEIs) with defined tyrosine modifications are a class of novel polymers designed for improved siRNA delivery. Their interactions with biomacromolecules are still poorly described. This paper analyzes the interaction of different tyrosine-modified PEIs with human serum albumin as the most abundant serum protein. The ability of tyrosine modified, linear or branched PEIs to bind human serum albumin (HSA) was analyzed and further characterized. The interaction with hydrophobic parts of protein were studied using 1- nilinonaphthalene-8-sulfonic acid (ANS) and changes in the HSA secondary structure were evaluated using circular dichroism (CD). Complex formation and sizes were studied by transmission electron microscopy (TEM) and dynamic light scattering methods (DLS). We demonstrate that tyrosine modified PEIs are able to bind human serum albumin. Based on thermodynamic studies, van der Waals interaction, H-bonding and hydrophobic interactions are determined as main molecular forces involved in complex formation. Analysis of secondary structures revealed that the polymers decreased α-helix content, while increasing levels of randomly folded structures. Complex formation was confirmed by TEM and DLS. These findings are crucial for understanding polymer-protein interactions and the properties of nanoparticles.

Surfactin-like lipopeptides from Bacillus clausii efficiently bind to spike glycoprotein of SARS-CoV-2

The coronavirus disease 2019 (COVID-19) rapidly spread across the globe, infecting millions and causing hundreds of deaths. It has been now around three years but still, it remained a serious threat worldwide, even after the availability of some vaccines. Bio-surfactants are known to have antiviral activities and might be a potential alternative for the treatment of SARS-CoV-2 infection. In the present study, we have isolated and purified, a surfactin-like lipopeptide produced by a probiotic bacterial strain Bacillus clausii TS. Upon purification and characterization with MALDI analysis, the molecular weight of the lipopeptide is confirmed as 1037 Da (similar to surfactin C) which is known to have antiviral activities against various enveloped viruses. Purified surfactin-like lipopeptide showed efficient binding and inhibition of SARS-CoV-2 spike (S1) protein, revealed by competitive ELISA assay. Further, we have explored the complete thermodynamics of the inhibitory binding of surfactin-like lipopeptide with S1 protein using isothermal titration calorimetric (ITC) assay. ITC results are in agreement with ELISA with a binding constant of 1.78 × 10-4 M-1. For further validation of the inhibitory binding of surfactin-like lipopeptide with S1 protein and its receptor binding domain (RBD), we performed molecular docking, dynamics, and simulation experiments. Our results suggested that surfactin could be a promising drug agent for the spike protein targeting drug development strategy against SARS-CoV-2 and other emerging variants.Communicated by Ramaswamy H. Sarma.

Explanation of inconsistencies in the determination of human serum albumin thermal stability

Thermal denaturation of human serum albumin has been the subject of many studies in recent decades, but the results of these studies are often conflicting and inconclusive. To clarify this, we combined different spectroscopic and calorimetric techniques and performed an in-depth analysis of the structural changes that occur during the thermal unfolding of different conformational forms of human serum albumin. Our results showed that the inconsistency of the results in the literature is related to the different quality of samples in different batches, methodological approaches and experimental conditions used in the studies. We confirmed that the presence of fatty acids (FAs) causes a more complex process of the thermal denaturation of human serum albumin. While the unfolding pathway of human serum albumin without FAs can be described by a two-step model, consisting of subsequent reversible and irreversible transitions, the thermal denaturation of human serum albumin with FAs appears to be a three-step process, consisting of a reversible step followed by two consecutive irreversible transitions.

Direct Application of 3-Maleimido-PROXYL for Proving Hypoalbuminemia in Cases of SARS-CoV-2 Infection: The Potential Diagnostic Method of Determining Albumin Instability and Oxidized Protein Level in Severe COVID-19

Oxidative stress and the albumin oxidized form can lead to hypoalbuminemia, which is a predisposing factor for reduced treatment effectiveness and an increased mortality rate in severe COVID-19 patients. The aim of the study is to evaluate the application of free radical 3-Maleimido-PROXYL and SDSL-EPR spectroscopy in the in vitro determination of ox/red HSA in serum samples from patients with SARS-CoV-2 infection. Venous blood was collected from patients intubated (pO₂ < 90%) with a positive PCR test for SARS-CoV-2 and controls. At the 120th minute after the incubation of the serum samples from both groups with the 3-Maleimido-PROXYL, the EPR measurement was started. The high levels of free radicals were determined through the nitroxide radical TEMPOL, which probably led to increased oxidation of HSA and hypoalbuminemia in severe COVID-19. The double-integrated spectra of 3-Maleimido-PROXYL radical showed a low degree of connectivity due to high levels of oxidized albumin in COVID-19 patients. The low concentrations of reduced albumin in serum samples partially inhibit spin-label rotation, with A_max values and ΔH₀ spectral parameters comparable to those of 3-Maleimido-PROXYL/DMSO. Based on the obtained results, we suggest that the stable nitroxide radical 3-Maleimido-PROXYL can be successfully used as a marker to study oxidized albumin levels in COVID-19.

Phase Angle and Handgrip Strength as Predictors of Clinical Outcomes in Hospitalized COVID-19 Patients

Phase angle (PhA) and muscle strength are predictors of clinical outcomes in critically ill patients. Malnutrition may affect body composition measurements. The aim of this prospective study was to investigate the association between PhA and handgrip strength (HGS), and clinical outcomes in hospitalized COVID-19 patients. The study included a total of 102 patients. Both PhA and HGS were measured twice, within 48 h of hospital admission and on the 7th day of hospitalization. The primary outcome was the clinical status on the 28th day of hospitalization. Secondary outcomes included the hospital length of stay (LOS), the concentrations of ferritin, C-reactive protein and albumin, oxygen requirements and the severity of pneumonia. A one-way analysis of variance (ANOVA) test and Spearman rS correlation coefficient were used for statistical analysis. No differences were found for PhA [on day 1 (p = 0.769) and day 7 (p = 0.807)] and the primary outcome. A difference was found between HGS on day 1 and the primary outcome (p = 0.008), while no difference was found for HGS on day 7 (p = 0.476). Body mass index was found to be associated with the oxygen requirement on day 7 (p = 0.005). LOS was correlated neither with PhA (rs = −0.081, p = 0.422) nor with HGS (rs = 0.137, p = 0.177) on the first day. HGS could be a useful indicator of clinical outcomes in COVID-19 patients, while PhA does not seem to have a clinical impact. However, further research is needed to validate the results of our study.

Relationship between Plasma Levels of Zinc and Magnesium with the Treatment Process and Mortality Risk in COVID-19 Patients

Background

The COVID-19 pandemic is considered a major health problem all over the world which has caused extensive and worldwide mortality and morbidities along with vast economic and political impact. Limitations of our knowledge and controversies in treatment modalities make the control and management of this disease more difficult. The status of electrolytes especially Mg and Zn in plasma and its correlation with the clinical situation and criteria for recovery has been investigated in various studies. Limited data in Iran mandate the design of a trial for evaluating our critically ill patients. We designed this study to investigate the correlation between plasma levels of Mg and Zn and the outcome including patients' need for assisted/controlled ventilation, time required for weaning, length of ICU stay, and probable cause of death.

Materials and Methods

413 patients with severe respiratory signs of COVID-19 disease who were admitted to the ICUs of 3 medical centers of Shahid Beheshti University of Medical Sciences were evaluated for plasma levels of Mg and Zn. Supplemental therapy was introduced when needed and was followed until discharge from ICU or death. All recorded data were analyzed by statistical methods and results were compared with similar studies.

Results

20.6% and 35.1% of all participants had low serum levels of Mg and Zn, respectively. 11 patients (2.7%) died through the treatment period. 56.9% and 61.0% of participants received Mg and Zn supplements, respectively.

Conclusion

According to our results, serum Mg and Zn levels did not show a significant correlation with the risk of death due to severe COVID-19 disease, prolonged assisted ventilation, or duration of ICU stay. There was no significant association between Mg and Zn supplementation with the risk of death due to severe COVID-19; however, it showed an inverse relationship with the time required for assisted ventilation and the duration of ICU stay. It seems that Mg and Zn supplementation can be useful in preventing or managing some of the morbidities among COVID-19 patients.

Graphene Oxide Decreases Pro-Inflammatory Proteins Production in Skeletal Muscle Cells Exposed to SARS-CoV-2 Spike Protein

Aim

The experiments aimed to document the presence of the ACE2 receptor on human muscle cells and the effects of the interaction of these cells with the spike protein of the SARS-CoV-2 virus in terms of induction of pro-inflammatory proteins, as well as to assess the possibility of reducing the pool of these proteins with the use of graphene oxide (GO) flakes.

Methods

Human Skeletal Myoblast (HSkM), purchased from Gibco were maintained in standard condition according to the manufacturer's instruction. The cells were divided into 4 groups; 1. C-control, 2. S-with addition of spike protein, 3. GO-with the addition of graphene oxide, 4. GO-S-with addition of GO followed by the addition of S protein. Protein S (PX-COV-P049) was purchased from ProteoGenix (France). GO was obtained from Advanced Graphene Products (Zielona Gora, Poland). The influence of all the factors on the morphology of cells was investigated using light and confocal microscopy. ACE2 protein expression on muscle cells was visualized and 40 pro-inflammatory cytokines were investigated using the membrane antibody array method. The protein profile of the lysate of cells from individual groups was also analyzed by mass spectrometry.

Conclusion

The experiments confirmed the presence of the ACE2 receptor in human skeletal muscle cells. It has also been documented that the SARS-CoV-2 virus spike protein influences the activation of selected pro-inflammatory proteins that promote cytokine storm and oxidative stress in muscle cells. The use of low levels of graphene oxide does not adversely affect muscle cells, reducing the levels of most proteins, including pro-inflammatory proteins. It can be assumed that GO may support anti-inflammatory therapy in muscles by scavenging proteins that activate cytokine storm.

Chiral 8-aminoBODIPY-based fluorescent probes with site selectivity for the quantitative detection of HSA in biological samples

Human serum albumin (HSA) is one of the vital proteins in blood serum, and its optimum level is a reflection of the physiological well-being of an individual. Any abnormalities in serum HSA levels could often be a sign of disguised physiological disorders. The importance of fast and accurate determination of serum HSA levels has led to the development of various quantification methods. Among these, fluorescence-based methods employ molecular probes capable of producing selective responses on interaction with HSA. Herein, we report chiral 8-aminoBODIPY-based probes having blue emission for the quantitative detection of HSA in buffer and human blood serum. A pair of 8-aminoBODIPY enantiomers, namely R-PEB and S-PEB, were synthesized. They exhibited a fast 'turn-on' fluorescence response towards HSA, allowing its detection and quantification. In PBS buffer, R-PEB and S-PEB showed very good sensitivity with a limit of detection (LoD) of 25 nM (K_D = 9.84 ± 0.14 μM) and 39 nM (K_D = 18.67 ± 0.21 μM), respectively. The linear relationship observed between the fluorescence intensity of R-PEB/S-PEB and the HSA concentration in serum samples allowed us to generate a reference curve for HSA estimation for practical applications. Examination of unknown serum samples showed a good correlation with the results obtained by the benchmark BCG method. Interestingly, the difference in these probes' dissociation constants and LoD indicated their differential binding to HSA. Considering the availability of multiple ligand binding sites in HSA, their binding preferences were investigated in detail by displacement assays using site-specific drugs. These studies showed the preferential affinity of R-PEB towards site II, which was further substantiated using molecular docking studies. However, these displacement assays could not identify the preferred binding site of S-PEB. Blind docking studies indicated that S-PEB occupied a site closer to FA5. Selective binding of R-PEB to site II and its characteristic photophysical response can be utilized to quickly screen potential site II binding drugs.

Label-Free Analysis of Binding and Inhibition of SARS-Cov-19 Spike Proteins to ACE2 Receptor with ACE2-Derived Peptides by Surface Plasmon Resonance

SARS-CoV-2 has been shown to enter and infect human cells via interactions between spike protein (S glycoprotein) and angiotensin-converting enzyme 2 (ACE2). As such, it may be possible to suppress the infection of the virus via the blocking of this binding interaction through the use of specific peptides that can mimic the human ACE 2 peptidase domain (PD) α 1-helix. Herein, we report the use of competitive assays along with surface plasmon resonance (SPR) to investigate the effect of peptide sequence and length on spike protein inhibition. The characterization of these binding interactions helps us understand the mechanisms behind peptide-based viral blockage and develop SPR methodologies to quickly screen disease inhibitors. This work not only helps further our understanding of the important biological interactions involved in viral inhibition but will also aid in future studies that focus on the development of therapeutics and drug options. Two peptides of different sequence lengths, [30-42] and [22-44], based on the α 1-helix of ACE2 PD were selected for this fundamental investigation. In addition to characterizing their inhibitory behavior, we also identified the critical amino acid residues of the RBD/ACE2-derived peptides by combining experimental results and molecular docking modeling. While both investigated peptides were found to effectively block the RBD residues known to bind to ACE2 PD, our investigation showed that the shorter peptide was able to reach a maximal inhibition at lower concentrations. These inhibition results matched with molecular docking models and indicated that peptide length and composition are key in the development of an effective peptide for inhibiting biophysical interactions. The work presented here emphasizes the importance of inhibition screening and modeling, as longer peptides are not always more effective.

Thermodynamics of benzoquinone-induced conformational changes in nucleic acids and human serum albumin

Biological macromolecules such as proteins, nucleic acids, carbohydrates and lipids, play a crucial role in biochemical and molecular processes. Thus, the study of the structure-function relationship of biomolecules in presence of ligands is an important aspect of structural biology. The current communication describes the chemico-biological interaction between benzene metabolite para-benzoquinone (BQ) with B-form of nucleic acids (B-DNA) and human serum albumin (HSA). The binding ability of HSA towards bromocresol green (BCG) was significantly suppressed when exposed to increasing concentrations of BQ in the presence of various physiological buffers. Further, the native fluorescence of HSA was drastically reduced and the secondary structures of HSA were significantly compromised with increasing concentrations of BQ. In vitro and in silico studies also revealed that BQ binds to domains I and II of HSA and thus altering the conformation of HSA which may potentially affect plasma osmotic pressure, as well as the binding and transport of numerous endogenous and exogenous molecules. Similarly, BQ interacts directly to the GC region of B-DNA particularly in the minor groove which was also assessed by computational docking studies. Isothermal titration calorimetry data suggest higher binding affinity of BQ towards DNA than HSA. Various spectroscopic observations also suggest that BQ binds to DNA preferably in the minor grooves. Thus, the results revealed that BQ may play a key role in inducing mutagenicity, either by formation of adducts on GC regions or by accelerating oxidative damage to biomacromolecules through chemico-biological interactions.

Enzyme linked oligonucleotide assay for the sensitive detection of SARS-CoV-2 variants

The exponential spread of COVID-19 has prompted the need to develop a simple and sensitive diagnostic tool. Aptamer-based detection assays like ELONA are promising since they are inexpensive and sensitive. Aptamers have advantages over antibodies in wide modification, small size, in vitro selection, and stability under stringent conditions, which aid in scalable and reliable detection. In this work, we used aptamers against SARS-CoV-2 RBD S protein to design a simple and sensitive ELONA detection tool. Screening CoV2-RBD-1C and CoV2-RBD-4C aptamers and optimizing assay conditions led to the development of a direct ELONA that can detect SARS-CoV-2 RBD S glycoprotein in buffer solution and 0.1 % human nasal fluid with a detection limit of 2.16 ng/mL and 1.02 ng/mL, respectively. We detected inactivated Alpha, Wuhan, and Delta variants of SARS-CoV-2 with the detection limit of 3.73, 5.72, and 6.02 TCID₅₀/mL, respectively. Using the two aptamers as capture and reporter elements, we designed a more sensitive sandwich assay to identify the three SARS-CoV-2 variants employed in this research. As predicted, a lower detection limit was obtained. Sandwich assay LOD was 2.31 TCID₅₀/mL for Alpha, 1.15 TCID₅₀/mL for Wuhan, and 2.96 TCID₅₀/mL for Delta. The sensitivity of sandwich ELONA was validated using Alpha and Wuhan variants spiked in 0.1% human nasal fluid sample condition and were detected in 1.41 and 1.79 TCID₅₀/mL LOD, respectively. SEM was used to visualize the presence of viral particles in the Delta variant sample. The effective detection of SARS-CoV-2 in this study confirms the potential of our aptamer-based technique as a screening tool.

Study of Albumin Oxidation in COVID-19 Pneumonia Patients: Possible Mechanisms and Consequences

Oxidative stress induced by neutrophils and hypoxia in COVID-19 pneumonia leads to albumin modification. This may result in elevated levels of advanced oxidation protein products (AOPPs) and advanced lipoxidation end-products (ALEs) that trigger oxidative bursts of neutrophils and thus participate in cytokine storms, accelerating endothelial lung cell injury, leading to respiratory distress. In this study, sixty-six hospitalized COVID-19 patients with respiratory symptoms were studied. AOPPs-HSA was produced in vitro by treating human serum albumin (HSA) with chloramine T. The interaction of malondialdehyde with HSA was studied using time-resolved fluorescence spectroscopy. The findings revealed a significantly elevated level of AOPPs in COVID-19 pneumonia patients on admission to the hospital and one week later as long as they were in the acute phase of infection when compared with values recorded for the same patients 6- and 12-months post-infection. Significant negative correlations of albumin and positive correlations of AOPPs with, e.g., procalcitonin, D-dimers, lactate dehydrogenase, aspartate transaminase, and radiological scores of computed tomography (HRCT), were observed. The AOPPs/albumin ratio was found to be strongly correlated with D-dimers. We suggest that oxidized albumin could be involved in COVID-19 pathophysiology. Some possible clinical consequences of the modification of albumin are also discussed.

Low serum albumin: A neglected predictor in patients with cardiovascular disease

Albumin, the most abundant circulating protein in blood, is an essential protein which binds and transports various drugs and substances, maintains the oncotic pressure of blood and influences the physiological function of the circulatory system. Albumin also has anti-inflammatory, antioxidant, and antithrombotic properties. Evidence supports albumin's role as a strong predictor of cardiovascular (CV) risk in several patient groups. Its protective role extends to those with coronary artery disease, heart failure, hypertension, atrial fibrillation, peripheral artery disease or ischemic stroke, as well as those undergoing revascularization procedures or with aortic stenosis undergoing transcatheter aortic valve replacement, and patients with congenital heart disease and/or endocarditis. Hypoalbuminemia is a strong prognosticator of increased all-cause and CV mortality according to several cohort studies and meta-analyses in hospitalized and non-hospitalized patients with or without comorbidities. Normalization of albumin levels before discharge lowers mortality risk, compared with hypoalbuminemia before discharge. Modified forms of albumin, such as ischemia modified albumin, also has prognostic value in patients with coronary or peripheral artery disease. When albumin is combined with other risk factors, such as uric acid or C-reactive protein, the prognostic value is enhanced. Although albumin supplementation may be a plausible approach, its efficacy has not been established and in patients with hypoalbuminemia, priority is focused on diagnosing and managing the underlying condition. The CV effects of hypoalbuminemia and relevant issues are considered in this review. Large cohort studies and meta-analyses are tabulated and the physiologic effects of albumin and the deleterious effects of low albumin are pictorially illustrated.

Fibrinogen-to-Albumin Ratio and Blood Urea Nitrogen-to-Albumin Ratio in COVID-19 Patients: A Systematic Review and Meta-Analysis

Fibrinogen-to-albumin ratio (FAR) and blood urea nitrogen-to-albumin ratio (BAR) are inflammatory biomarkers that have been associated with clinical outcomes of multiple diseases. The objective of this study is to evaluate the association of these biomarkers with the severity and mortality of COVID-19 patients. A systematic search was performed in five databases. Observational studies that reported the association between FAR and BAR values with the severity and mortality of COVID-19 patients were included. Random-effects models were used for meta-analyses, and effects were expressed as Odds Ratio (OR) and their 95% confidence intervals (CI). Publication bias was assessed using the Begg test, while the quality assessment was assessed using the Newcastle Ottawa Scale. A total of 21 studies (n = 7949) were included. High FAR values were associated with a higher risk of severity (OR: 2.41; 95% CI 1.41−4.12; p < 0.001) and mortality (OR: 2.05; 95% CI 1.66−2.54; p < 0.001). High BAR values were associated with higher risk of mortality (OR: 4.63; 95% CI 2.11−10.15; p < 0.001). However, no statistically significant association was found between BAR values and the risk of severity (OR: 1.16; 95% CI 0.83−1.63; p = 0.38). High FAR and BAR values were associated with poor clinical outcomes.

A point-of-care microfluidic channel-based device for rapid and direct detection of fibrinogen in whole blood

Hemorrhage is the leading cause of preventable death in civilian and battlefield traumatic injuries. Patients with severe traumatic hemorrhagic shock are more likely to be deficient in fibrinogen than those with other coagulation factors, and hypofibrinogenemia is an independent risk factor for mortality. Thus, rapid detection of fibrinogen levels is of great importance in these patients during damage control resuscitation. Plasma is used as an analyte in fibrinogen detection, which restricts the use of existing devices in emergencies. To meet the needs of on-site detection, we developed a point-of-care microfluidic channel-based device for direct measurement of fibrinogen concentration in whole blood. In our method, thrombin is dispersed on a reaction strip to initiate conversion of fibrinogen to fibrin. The permeability of the resulting blood clots depends on the fibrinogen level. A hydrophobic plastic protection flake between the reaction strip and a wicking strip is then removed to allow flow of unclotted blood. The rate of blood flow along the wicking strip was inversely related to the fibrinogen concentration. The whole process could be completed in as fast as 5 minutes for a whole blood sample size of 150 μL, and yielded accurate results ranging from 0 to 4 g L^-1, which were unaffected by Ca²⁺, blood lipids, hematocrit, warfarin and tissue plasminogen activators (tPAs). Results using clinical whole blood samples were also highly consistent with those using an automatic coagulation analyzer, yielding a Pearson correlation coefficient of up to 0.919. This approach has potential for allowing rapid diagnosis of fibrinogen concentration in critically ill bleeding patients in different settings, thus helping to judge the suitability of fibrinogen replacement therapy (FRT) in cases of emergency bleeding and in patients at risk of thrombosis due to hyperfibrinogenemia.

An insight into the interaction between Indisulam and human serum albumin: Spectroscopic method, computer simulation and in vitro cytotoxicity assay

Indisulam (IDM) is a sulfanilamide anticancer agent and has been identified as a molecular glue recently. It shows potential for novel therapies development and brings more hope for curing human diseases. The affinity between molecular glues and plasma protein makes it significant to understand the characteristics of such substances. Therefore, the interaction between IDM and human serum albumin (HSA) was explored through solvent experiments, computer simulation experiments, enzyme kinetics experiments, and cell viability assay. The results revealed that IDM and HSA spontaneously formed stable binary complex with the binding constant of the order 10⁵ M^-1. IDM inserted in the site I of HSA, resulting the change in HSA secondary structure. And π electrons in IDM's benzene rings, as well as van der Waals forces and the H-bond, all helped to stabilize the HSA-IDM complex. The results of molecular dynamic simulation (MD) corresponded with the results from solvent experiment well. For instance, there were approximately 1-5 H-bonds between IDM and HSA. Lys199 and Arg218 were crucial energy contributors in the binding process. The esterase-like activity experiment confirmed that IDM inhibited the catalytic activity of HSA. In addition, cell experiment revealed that serum albumin can significantly reduce the cytotoxicity of IDM towards human embryonic kidney 293T (HEK293T) cells.

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.

Inclusion complex of 20(S)-protopanaxatriol with modified β-cyclodextrin: Characterization, solubility, and interaction with bovine serum albumin

20(S)-protopanaxatriol (PPT) is one of the ginsenosides isolated from Panax ginseng which have many pharmaceutical activities. However, the poor water solubility of PPT restrict its applications. Herein, a novel bridged-bis-[6-(3,3'-(ethylenedioxy) bis (propylamine))-6-deoxy-β-cyclodextrin] (EDBA-bis-β-CD) was designed and synthesized, and the inclusion complex (IC) of EDBA-bis-β-CD with PPT was successfully prepared in the solid state, and characterized by UV, ¹H NMR, 2D ROESY, FT-IR, XRD and SEM and molecular modelling methods. The continuous variation method analysis indicated that the stoichiometry of the IC was 1:1. UV-vis spectral analysis demonstrated the binding constant K_s was 995.94 M^-1, and the solubility study showed that the solubility of PPT improved 290 times. The interaction of the IC with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy. The results indicated that fluorescence quenching of BSA by IC was static quenching. Thermodynamic studies showed that van der Waals forces and hydrogen bonding play significant roles in interaction. The esterase-like activity of BSA in the presence of IC showed that it reduce the esterase activity of BSA in a competitive manner. Furthermore, molecular docking and molecular dynamics simulations for EDBA-bis-β-CD/PPT and BSA/IC systems were generated to provide information on the stability and the forces in the binding.

A near-infrared dicyanoisophorone-based fluorescent probe for discriminating HSA from BSA

Despite the rapid development of fluorescent probe techniques for the detection of human serum albumin (HSA), a probe that discriminates between HSA and bovine serum albumin (BSA) is still a challenging task, since their similar chemical structures. As a continuation of our work, herein, a dicyanoisophorone-based fluorescent probe DCO2 is systematically studied for discrimination of HSA from BSA. The photophysical and sensing performances of DCO2, including basic spectroscopic properties, sensing sensitivity, and selectivity, exhibits that DCO2 could selectively bind with HSA and display remarkable fluorescence enhancement (∼254-fold) at 685 nm. The gap of the fluorescent response of DCO2 between HSA and BSA is an obvious increase from 21% to 73% compared to the previous probe DCO1. The sensing mechanism was elucidated by Job's plot, displacement experiment, and molecular docking, suggesting that the specific response to HSA originated from the rigid donor structure and steric hindrance. DCO2 could be buried in the DS1 pocket of HSA, and only partly wedged into the DS1 pocket of BSA with exposing twisted N,N-diethylamino group outside. Application studies indicated that DCO2 has well detective behavior for HSA in the biological fluids. This work could provide a new approach to design HSA-specific near-infrared fluorescence probes.

Human interaction targets of SARS-COV-2 spike protein: A systematic review

Objectives:

The development of effective targeted therapy and drug-design approaches against the SARS-CoV-2 is a universal health priority. Therefore, it is important to assess possible therapeutic strategies against SARS-CoV-2 via its most interaction targets. The present study aimed to perform a systematic review on clinical and experimental investigations regarding SARS-COV-2 interaction targets for human cell entry.

Methods:

A systematic search using relevant MeSH terms and keywords was performed in PubMed, Scopus, Embase, and Web of Science (ISI) databases up to July 2021. Two reviewers independently assessed the eligibility of the studies, extracted the data, and evaluated the methodological quality of the included studies. Additionally, a narrative synthesis was done as a qualitative method for data gathering and synthesis of each outcome measure.

Results:

A total of 5610 studies were identified, and 128 articles were included in the systematic review. Based on the results, spike antigen was the only interaction protein from SARS-CoV-2. However, the interaction proteins from humans varied including different spike receptors and several cleavage enzymes. The most common interactions of the spike protein of SARS-CoV-2 for cell entry were ACE2 (entry receptor) and TMPRSS2 (for spike priming). A lot of published studies have mainly focused on the ACE2 receptor followed by the TMPRSS family and furin. Based on the results, ACE2 polymorphisms as well as spike RBD mutations affected the SARS-CoV-2 binding affinity.

Conclusion:

The included studies shed more light on SARS-CoV-2 cellular entry mechanisms and detailed interactions, which could enhance the understanding of SARS-CoV-2 pathogenesis and the development of new and comprehensive therapeutic approaches.