Glycation Of Human Serum Albumin Research Articles

Effect of ellagitannin metabolites ellagic acid and urolithins A-D on the non-enzymatic glycation of human serum albumin and inhibiting mechanisms

Effect of ellagitannin metabolites ellagic acid and urolithins A-D on the non-enzymatic glycation of human serum albumin and inhibiting mechanisms

Protective effect of colchicine on albumin glycation and cellular oxidative stress: Insights into diabetic cardiomyopathy.

The present work elucidates the role of colchicine (COL) on albumin glycation and cellular oxidative stress in diabetic cardiomyopathy (DCM). Human serum albumin (HSA) was glycated with methylglyoxalin the presence of COL (2.5, 3.75, and 5 µM), whereas positive and negative control samples were maintained separately. The effects of COL on HSA glycation, structural and functional modifications in glycated HSA were analyzed using different spectroscopical andfluorescence techniques. Increased fructosamine, carbonyl, and pentosidine formation in glycated HSA samples were inhibited in the presence of COL. Structural conformation of HSA and glycated HSA samples was examined by field emission scanning electron microscopy, circular dichroism, Fourier transform infrared, and proton nuclear magnetic resonance analyses, where COL maintained both secondary and tertiary structures of HSA against glycation. Functional marker assays included ABTS•+ radical scavenging and total antioxidant activities, advanced oxidative protein product formation, and turbidimetry, which showed preserved functional properties of glycated HSA in COL-containing samples. Afterward, rat cardiomyoblast (H9c2 cell line) was treated with glycated HSA-COL complex (400 μg/mL) for examining various cellular antioxidants (nitric oxide, catalase, superoxide dismutase, and glutathione) and detoxification enzymes (aldose reductase, glyoxalase I, andII) levels. All three concentrations of COL exhibited effective anti-glycation properties, enhanced cellular antioxidant levels, and detoxification enzyme activities. The report comprehensively analyzes the potential anti-glycation and properties of COL during its initial assessment.

The Thiol Group Reactivity and the Antioxidant Property of Human Serum Albumin Are Controlled by the Joint Action of Fatty Acids and Glucose Binding.

The binding of ubiquitous serum ligands (free fatty acids) to human serum albumin (HSA) or its glycation can affect thiol group reactivity, thus influencing its antioxidant activity. The effects of stearic acid (SA) and glucose binding on HSA structural changes and thiol group content and reactivity were monitored by fluoroscopy and the Ellman method during a 14-day incubation in molar ratios to HSA that mimic pathophysiological conditions. Upon incubation with 5 mM glucose, HSA glycation was the same as HSA without it, in three different HSA:SA molar ratios (HSA:SA-1:1-2-4). The protective effect of SA on the antioxidant property of HSA under different glucose regimes (5-10-20 mM) was significantly affected by molar ratios of HSA:SA. Thiol reactivity was fully restored with 5-20 mM glucose at a 1:1 HSA:SA ratio, while the highest thiol content recovery was in pathological glucose regimes at a 1:1 HSA:SA ratio. The SA affinity for HSA increased significantly (1.5- and 1.3-fold, p < 0.01) with 5 and 10 mM glucose compared to the control. These results deepen the knowledge about the possible regulation of the antioxidant role of HSA in diabetes and other pathophysiological conditions and enable the design of future HSA-drug studies which, in turn, is important for clinicians when designing information-based treatments.

Insights into the conformational, secondary structural, dynamical and hydration pattern changes of glucose mediated glycated HSA: a molecular dynamics approach

The robust structural nature of human serum albumin (HSA) is responsible for its multifarious functional property. The site specific glycation of HSA due to hyperglycaemia (excess glucose) causes structural changes which have an impact on the functioning of the protein. This work investigates the effects of glucose-mediated glycation in the altered inter-domain motion, distorted binding site conformation and modified hydration patterns, Trp214 orientation, and secondary structure transition using simulation approach. Here we have observed an increase of turns in the helices of glycated HSA, which modulates the open-close conformation of Sudlow I & II. The secondary structure changes of glycated HSA indicate plausible reduction in the alpha helical content in the helices which participates in ligand binding. It also affects geometrical features of drug binding sites (Sudlow I and II) such as volume and hydration. We found that glycation disturbs domain specific mobility patterns of HSA, a substantial feature for albumin drug binding ability which is also correlated with changes in the local environment of Trp214. Communicated by Ramaswamy H. Sarma

Inhibition of toxic metal-alpha synuclein interactions by human serum albumin.

Human serum albumin (HSA), the most abundant protein in plasma and cerebrospinal fluid, not only serves as a crucial carrier of various exogenous and endogenous ligands but also modulates the aggregation of amyloidogenic proteins, including alpha synuclein (αSyn), which is associated with Parkinson's disease and other α-synucleinopathies. HSA decreases αSyn toxicity through the direct binding to monomeric and oligomeric αSyn species. However, it is possible that HSA also sequesters metal ions that otherwise promote aggregation. Cu(ii) ions, for example, enhance αSyn fibrillization in vitro, while also leading to neurotoxicity by generating reactive oxygen species (ROS). However, it is currently unclear if and how HSA affects Cu(ii)-binding to αSyn. Using an integrated set of NMR experiments, we show that HSA is able to chelate Cu(ii) ions from αSyn more efficiently than standard chelators such as EDTA, revealing an unexpected cooperativity between the HSA metal-binding sites. Notably, fatty acid binding to HSA perturbs this cooperativity, thus interfering with the sequestration of Cu(ii) ions from αSyn. We also observed that glycation of HSA diminished Cu(ii)-binding affinity, while largely preserving the degree of cooperativity between the HSA metal-binding sites. Additionally, our results show that Cu(ii)-binding to HSA stabilizes the interactions of HSA with αSyn primarily at two different regions, i.e. the N-terminus, Tyr 39 and the majority of the C-terminus. Our study not only unveils the effect of fatty acid binding and age-related posttranslational modifications, such as glycation, on the neuroprotective mechanisms of HSA, but also highlights the potential of αSyn as a viable NMR-based sensor to investigate HSA-metal interactions.

Synthesis, Characterization, Antiglycation Evaluation, Molecular Docking, and ADMET Studies of 4-Thiazolidinone Derivatives.

The design and development of new small-molecule glycation inhibitors are essential for preventing various chronic diseases, including diabetes mellitus, immunoinflammation, cardiovascular, and neurodegenerative diseases. 4-Thiazolidinone or thiazolidine-4-one is a well-known heterocyclic compound with the potential to inhibit the formation of advanced glycation end products. In the present work, we report the synthesis and characterization of four new 5-arylidene 3-cyclopropyl-2-(phenylimino)thiazolidin-4-one (1-4) compounds and their human serum albumin glycation inhibitory activity. One of the compounds 5-(2H-1,3-benzodioxol-5-ylmethylidene)-3-cyclopropyl-2-(phenylimino)-1,3-thiazolidin-4-one (3) showed potent inhibition in the synthesis of initial, intermediary, and final products of glycation reactions. Besides, conformational changes in the α-helix and β-sheet (due to hyperglycemia) were also found to be reversed upon the addition of (3). Experimental findings were complemented by computational [molecular docking, ADME/Tox, and density functional theory (DFT)] studies. The docking scores of the compounds were in order 1 > 3 > 2 > 4, indicating the importance of the polar group at the 5-arylidene moiety. The results of ADME/Tox and DFT calculations revealed the safe nature of the compounds with high drug-likeness and stability. Overall, we speculate that the results of this study could provide valuable insights into the biological activity of 4-thiazolidinones.

Modification of fullerene with amino acids as a method for obtaining biocompatible materials with a protective effect

Fullerenes and their derivatives have great potential for use as materials for medicine and biology. Fullerenes can enter into various reactions due to the presence of double bonds in their structure; it has also been repeatedly noted in the literature that the molecules have antiradical activity, biocompatibility, the ability to pass through biobarriers and immobilize various active molecules. In this work, a water-soluble adduct of C60 fullerene with glycine was synthesized, its physicochemical properties, biocompatibility were studied, and a protective effects toward collagen photodegradation as well as in the model reaction of human serum albumin glycation was shown.

Crosstalk between Aldosterone and Glycation through Rac-1 Induces Diabetic Nephropathy.

Background: Advanced glycation end products (AGEs) interaction with its receptor (RAGE) and aldosterone (Aldo) through the mineralocorticoid receptor (MR) activates Rac-1 and NF-κB independently in diabetic nephropathy (DN). However, the crosstalk of Aldo with AGEs-RAGE is still unresolved. Our study examined the impact of the AGEs-Aldo complex on renal cells and its effect on the RAGE-MR interaction. Methods and results: Glycation of human serum albumin (HSA) (40 mg/mL) with methylglyoxal (10 mM) in the presence of Aldo (100 nM) and aminoguanidine (AG) (100 nM) was performed. Glycation markers such as fructosamine and carbonyl groups and fluorescence of AGEs, pentosidine, and tryptophan followed by protein modification were measured. Renal (HEK-293T) cells were treated with the glycated HSA-Aldo (200 μg/mL) along with FPS-ZM1 and spironolactone antagonists for RAGE and Aldo, respectively, for 24 h. Glycation markers and esRAGE levels were measured. Protein and mRNA levels of RAGE, MR, Rac-1, and NF-κB were estimated. Glycation markers were enhanced with Aldo when albumin was only 14-16% glycated. AGEs-Aldo complex upregulated RAGE, MR, Rac-1 and NF-κB expressions. However, FPS-ZM1 action might have activated the RAGE-independent pathway, further elevating MR, Rac-1, and NF-κB levels. Conclusion: Our study concluded that the presence of Aldo has a significant impact on glycation. In the presence of AGEs-Aldo, RAGE-MR crosstalk exerts inflammatory responses through Rac-1 in DN. Insights into this molecular interplay are crucial for developing novel therapeutic strategies to alleviate DN in the future.

Antiglycation, antifibrillation and antioxidative effects of para coumaric acid and vitamin D; an in-vitro and in-silico comparative-cum-synergistic approach

Diabetes Mellitus is a metabolic disorder that results in impaired utilization of carbohydrates, lipids, and proteins. Severe hyperglycemia is its principal clinical symptom. Human serum albumin (HSA) is used as a model protein since it is viewed as a sign of glycaemic management because it is more likely to get glycated in diabetic people than other proteins. Para-coumaric acid (pCA), a phenolic acid, and Vitamin D (vit-D) are used as protective agents. In the present work, we deduce a synergistic-cum-comparative effect of pCA and vit-D, expecting some improvement in the efficacy of pCA when combined with vit-D. Methods employed are DPPH radical scavenging activity, In-vitro glycation of HSA, UV–vis spectroscopy, fluorescence analysis, and circular dichroism measurement. After treatment, increasein the absorbance and fluorescence intensity were reduced along with normalization of CD value. . The glycation-mediated fibrillation assessed by Congo-Red and Thioflavin T (ThT) were found to be diminishedwhen HSA was treated with equimolar concentration of p-CA and vit-D- treatment. Fructosamine adduct formation and lysine modificationwas also decreased, while inhibition to hemolysis and lipid peroxidation was found to increase upon treatment. The reactive oxygen species generation detection was also performed in lymphocytes treated with various protein samples. Docking results further confirmed theblocking some glycation-prone amino acids by both compounds. The study shows that the combination in the ratio of 1:1 has provided higher overall protection comparable to aminoguanidine (AG), the molecule which is utilized as a positive control.

Synergistic interaction between Bambusa arundinacea and Euphorbia hirta leaf extract on antioxidant, antiglycation and DNA protective properties.

Oxidative stress and enhanced non-enzymatic protein glycation result in the pathogenesis of various disorders in humans, including diabetes mellitus. This study examined the synergistic action of Bambusa arundinacea with Euphorbia hirta leaf extract for anti-oxidant potential, antiglycation effect on fructose-mediated proteins, and DNA-protective properties. The methanolic extract shows significantly (P&lt;0.01) higher total phenolic and flavonoid content when compared with ethyl acetate and hexane extract in both plants. The combined methanolic extract (CME) of both plants exhibits higher antioxidant potential, as indicated by the lower IC50 values obtained for DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity (4.82 μg/ml) and NO (nitric oxide) scavenging activity (3.94 μg/ml) with stronger Trolox equivalent antioxidant capacity when compared to B. arundinacea and E. hirta individually. The antiglycation analysis revealed that CME is more potent to inhibit fructose-mediated glycation of human serum albumin (HSA) at the early and middle stages. In addition to this, CME more effectively inhibits protein glycation in the late phase, which was confirmed by declining fluorescence intensity. Furthermore, a high degree of positive correlation was obtained between antioxidant and antiglycation capacities through Pearson’s correlation coefficient. The results also demonstrated that CME displays a synergistic effect in protecting DNA from oxidative damage and preventing the formation of glycation of DNA.

Increased therapeutic effect of nanotized silibinin against glycation and diabetes: An in vitro and in silico-based approach

BackgroundThe global prevalence of diabetes has increased sharply, with the number of cases expected to rise from 424.9 million in 2017 to 628.6 million by 2045. Flavonoids are plant derived molecules with well-established antioxidant potential in addition to other therapeutic properties. Silibinin is a naturally occurring flavonoid with antioxidant and antidiabetic properties. However, its rapid metabolism and low bioavailability limit its therapeutic effects. Aims & objectivesIn this study, we have synthesized the nanoformulation of silibinin and compared its antiglycating and antidiabetic potential with the soluble form. MethodologyThe inhibitory effect was tested on carbohydrate-hydrolyzing enzymes as well as glycation of human serum albumin (HSA). The structural and biochemical changes in HSA were assessed by spectroscopic analyses and different assays. Key findingsThe nanoforms were found to be better inhibitors of α-amylase and α-glucosidase compared to the bulk forms. Glycation of HSA in the presence of nano-silibinin resulted in the formation of lower level of early and advanced glycation products. This was also confirmed by spectroscopic studies and by estimating protein oxidation and free lysine residues. Molecular docking studies further supported the experimental outcomes. These results indicate that the nano form has significantly stronger antidiabetic and antiglycating effects than the bulk form. Nano-silibinin could therefore be recommended as a dietary supplement for diabetics to help control glycation and other associated complications.

Polyphenol loaded nanoparticles as antiglycating agents: A case study with human serum albumin

Advanced glycation end products (AGEs) formed through nonenzymatic glycation results in diseases including diabetic complications, Alzheimer’s disease and atherosclerosis etc. The development of novel antiglycating agents has thus become an important area of research. In our present work, we have reported the inhibitory activity of morin loaded PLGA NPs (MPNPs) on the D-ribose induced glycation of human serum albumin (HSA) based on spectroscopic studies. MPNPs were characterized by spectroscopic and microscopic techniques. HSA was incubated with ribose at 37 °C for one month and the formation of AGEs was confirmed from fluorescence studies, the increase in absorbance and the measurement of free amino groups. Further HSA and ribose mixtures incubated with MPNPs showed significant reduction in the extent of advanced glycation end product formation that were confirmed by UV-Vis and fluorescence spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI- ToF) techniques. The structural changes induced by MPNPs were further confirmed by circular dichroism studies. Our findings suggest that MPNPs have the potential to be used antiglycating agents.

Ursonic acid from Artemisia montana exerts anti-diabetic effects through anti-glycating properties, and by inhibiting PTP1B and activating the PI3K/Akt signaling pathway in insulin-resistant C2C12 cells

Artemisia is one of the largest genera in the plant family Asteraceae and has long been used in traditional medicine for its antitussive, analgesic, antihypertensive, antitoxic, antiviral, antimalarial, and anti-inflammatory properties. However, the anti-diabetic activity of Artemisia montana has not been broadly studied. The goal of this study was to determine whether extracts of the aerial parts of A. montana and its main constituents inhibit protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase activities. We isolated nine compounds from A. montana including ursonic acid (UNA) and ursolic acid (ULA), which significantly inhibited PTP1B with IC50 values of 11.68 and 8.73 μM, respectively. In addition, UNA showed potent inhibitory activity against α-glucosidase (IC50 = 61.85 μM). Kinetic analysis of PTP1B and α-glucosidase inhibition revealed that UNA was a non-competitive inhibitor of both enzymes. Docking simulations of UNA demonstrated negative binding energies and close proximity to residues in the binding pockets of PTP1B and α-glucosidase. Molecular docking simulations between UNA and human serum albumin (HSA) revealed that UNA binds tightly to all three domains of HSA. Furthermore, UNA significantly inhibited fluorescent AGE formation (IC50 = 4.16 μM) in a glucose-fructose-induced HSA glycation model over the course of four weeks. Additionally, we investigated the molecular mechanisms underlying the anti-diabetic effects of UNA in insulin-resistant C2C12 skeletal muscle cells and discovered that UNA significantly increased glucose uptake and decreased PTP1B expression. Further, UNA increased GLUT-4 expression level by activating the IRS-1/PI3K/Akt/GSK-3 signaling pathway. These findings clearly demonstrate that UNA from A. montana shows great potential for treatment of diabetes and its complications.

Silver nanoparticle interactions with glycated and non-glycated human serum albumin mediate toxicity.

Introduction: Biomolecules bind to and transform nanoparticles, mediating their fate in biological systems. Despite over a decade of research into the protein corona, the role of protein modifications in mediating their interaction with nanomaterials remains poorly understood. In this study, we evaluated how glycation of the most abundant blood protein, human serum albumin (HSA), influences the formation of the protein corona on 40nm silver nanoparticles (AgNPs) and the toxicity of AgNPs to the HepG2 human liver cell line. Methods: The effects of glycation on AgNP-HSA interactions were quantified using circular dichroism spectroscopy to monitor protein structural changes, dynamic light scattering to assess AgNP colloidal stability, zeta potential measurements to measure AgNP surface charge, and UV-vis spectroscopy and capillary electrophoresis (CE) to evaluate protein binding affinity and kinetics. The effect of the protein corona and HSA glycation on the toxicity of AgNPs to HepG2 cells was measured using the WST cell viability assay and AgNP dissolution was measured using linear sweep stripping voltammetry. Results and Discussion: Results from UV-vis and CE analyses suggest that glycation of HSA had little impact on the formation of the AgNP protein corona with protein-AgNP association constants of ≈2x107 M-1 for both HSA and glycated HSA (gHSA). The formation of the protein corona itself (regardless of whether it was formed from HSA or glycated HSA) caused an approximate 2-fold decrease in cell viability compared to the no protein AgNP control. While the toxicity of AgNPs to cells is often attributed to dissolved Ag(I), dissolution studies showed that the protein coated AgNPs underwent less dissolution than the no protein control, suggesting that the protein corona facilitated a nanoparticle-specific mechanism of toxicity. Overall, this study highlights the importance of protein coronas in mediating AgNP interactions with HepG2 cells and the need for future work to discern how protein coronas and protein modifications (like glycation) may alter AgNP reactivity to cellular organisms.

The effect of human serum albumin glycation on the binding of antidiabetic agent-exenatide; the multispectroscopic studies. Part II

The glycated human serum albumin (gHSA) interaction with antidiabetic agent – exenatide (exe) was investigated by spectroscopic techniques. The fluorescence spectroscopy showed an association between exe and protein as 4.57 × 104 M−1 (290 K), 3.33 × 104 M−1 (300K) and 2.54 × 104 M−1 (310K) and the number of binding sites were 1.15, 1.09, and 1.02, respectively. The binding process occurred spontaneously and the electrostatic bonds play a predominant role in the gHSA-exe interaction. The affinity drug to gHSA was studied in the presence of metal ions (Ca2+, Cr3+, Zn2+), which are often given as a supplement to the diet. Our study indicates that metal ions have an effect on the increase of the affinity of exenatide to glycated albumin and it is the result of the metal ion-exenatide-albumin interaction. Based on CD spectroscopy it is evident that exenatide has nonsignificant effect on the protein secondary structure, but the changes are visible in the presence of metal ions. Zeta potential measurements indicate instability of the system at lower concentration of the ligand - the effect is desired in point of view of pharmacology.

6-Formyl Umbelliferone, a Furanocoumarin from Angelica decursiva L., Inhibits Key Diabetes-Related Enzymes and Advanced Glycation End-Product Formation.

Over the years, great attention has been paid to coumarin derivatives, a set of versatile molecules that exhibit a wide variety of biological activities and have few toxic side effects. In this study, we investigated the antidiabetic potential of 6-formyl umbelliferone (6-FU), a novel furanocoumarin isolated from Angelica decursiva. Numerous pharmacological activities of 6-FU have been previously reported; however, the mechanism of its antidiabetic activity is unknown. Therefore, we examined the action of 6-FU on a few candidate-signaling molecules that may underlie its antidiabetic activity, including its inhibition of protein tyrosine phosphatase 1B (PTP1B), α-glucosidase, human recombinant aldose reductase (HRAR), and advanced glycation end-product (AGE) formation (IC50 = 1.13 ± 0.12, 58.36 ± 1.02, 5.11 ± 0.21, and 2.15 ± 0.13 μM, respectively). A kinetic study showed that 6-FU exhibited mixed-type inhibition against α-glucosidase and HRAR and competitive inhibition of PTP1B. Docking simulations of 6-FU demonstrated negative binding energies and close proximity to residues in the binding pockets of those enzymes. We also investigated the molecular mechanisms underlying 6-FU’s antidiabetic effects. 6-FU significantly increased glucose uptake and decreased PTP1B expression in insulin-resistant C2C12 skeletal muscle cells. Moreover, 6-FU (0.8–100 μM) remarkably inhibited the formation of fluorescent AGEs in glucose-fructose-induced human serum albumin glycation over the course of 4 weeks. The findings clearly indicate that 6-FU will be useful in the development of multiple target-oriented therapeutic modalities for the treatment of diabetes and diabetes-related complications.

The Burden of Impaired Serum Albumin Antioxidant Properties and Glyco-Oxidation in Coronary Heart Disease Patients with and without Type 2 Diabetes Mellitus.

Human serum albumin (HSA) has an important antioxidant activity due to the presence of the reduced cysteine at position 34, which represents the most abundant free thiol in the plasma. In oxidative-based diseases, HSA undergoes S-thiolation (THIO-HSA) with changes in the antioxidant function of albumin that could contribute to the progression of the disease. The aim of this study was to verify, for the first time, the different burdens of THIO-HSA, glycated HSA (GLY-HSA), and advanced glycation end products (AGE) accumulation both in type 2 diabetes mellitus (T2DM) patients and in non-diabetic patients, with or without coronary heart disease (CHD). In this study, we assessed the presence of modified forms of HSA, THIO-HSA, and GLY-HSA by means of mass spectrometry in 33 patients with both T2DM and CHD, in 31 patients with T2DM and without CHD, in 30 patients without diabetes with a history of CHD, and 27 subjects without diabetes and CHD. All the patients’ anthropometric and clinical data were recorded including age, sex, duration of diabetes, body mass index (BMI), blood pressure, and history of CHD defined with anamnestic data. Metabolic parameters, such as fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), lipids, pentosidine, AGE, receptor for advanced glycation end-products (RAGE) and its soluble form (sRAGE), were measured. AGE and pentosidine are significantly higher in T2DM patients with and without CHD with respect to non-diabetic patients with CHD and control subjects. RAGE levels are significantly higher in T2DM patients with respect to non-diabetic patients, and among T2DM patients, the group with CHD showed significantly higher RAGE levels than those without CHD (217 ± 171 pg/mL and 140 ± 61 pg/mL, respectively). Albumin isoforms discriminate between non-diabetic patients with CHD and T2DM patients with and without CHD and control subjects, with GLY-HSA levels higher in T2DM with and without CHD, and THIO-HSA higher in CHD patients without T2DM. Finally, we demonstrated that the oxidized forms of HSA can increase the expression of the inflammatory cytokine Tumor Necrosis Factor-alpha (TNFα) in monocytic cells. In patients with CHD, GLY-HSA and THIO-HSA have a different prevalent distribution, the first one prevailing in patients with T2DM and the second one in patients without T2DM. These findings suggest that albumin quality and homeostasis balance between glyco-oxidation and thiolation might have an impact on the antioxidant defense system in cardiovascular diseases.

Proteolytic Sensitivity, In Vitro Glycation Efficiency of Diabetic and Non-diabetic Human Serum Albumin

Background: Glycation of human serum albumin (HSA) leads to disturbances in its stability, activity, and other properties which, in turn, affect the functional properties of HSA. Modification of albumin by glycation shows considerable potential as a significant biochemical biomarker for diagnosing diabetes. The characteristics of the glycation process in proteins have not been fully examined yet and, therefore, there is insufficient knowledge about them in the field. Objectives: This study aimed to clarify the differences between diabetic and non-diabetic HSA as well as their structure-function relationship. Methods: The physiological and laboratory characteristics of glycated albumin as well as HSA were explored. A total of 30 subjects were enrolled in this study in which 15 normal healthy individuals were assigned into the control group, and 15 type-2 diabetic patients were included in the diabetic group. Patients with type-1 diabetes, pregnant women, and individuals with other diseases were excluded from the study. Protein estimation, polyacrylamide gel electrophoresis, ammonium sulphate fractionation, dialysis, glycation of HSA followed by gel electrophoresis of glycated samples, digestion of BSA, as well as HSA by α-chymotrypsin and their documentation and stoichiometry were all performed. Results: Various characteristic differences were observed between diabetic and non-diabetic HSA including proteolytic susceptibility and in vitro glycation efficiency. Hypoalbuminemia was, particularly, observed in diabetic patients, which was suggestive of a relationship between hyperglycemia and hypoalbuminemia. Conclusion: Peculiar contrariety between diabetic and non-diabetic HSA, specific differences in their glycation efficiencies, as well as proteolytic susceptibility and their innuendos were precisely traced out. It was concluded that albumin may have been regarded as a significant clinical biomarker for diagnosing diabetes.

Glycation end-products specific auto-antibodies in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease, which is highly inflammatory. Compared to a healthy control group, SLE patients exhibit a higher concentration of advanced glycation end products (AGEs) and a lower concentration of receptors for AGEs (RAGE) in serum, however, the exact aetiology is still unclear. In the present study, non-enzymatic glycation induced modification of human serum albumin (HSA) has been studied by biophysical techniques. Glycated HSA (G-HSA) was used as an antigen, and serum autoantibody levels were estimated in SLE and normal humans (NH) against it, using direct binding ELISA and competitive inhibition ELISA. Compared to N-HSA, remarkable structural modifications were observed in G-HSA. Modified HSA also showed increased pentosidine fluorescence (213.7 ± 13.4 AU). Glycation of HSA induced a conversion of α-helix and random coil to β-sheet and β-turns. Serum immuno assays results exhibited significantly (p < 0.001) higher binding of G-HSA with serum autoantibodies from SLE patients when compared with native HSA (N-HSA). Furthermore, competitive ELISA results showed significantly (p < 0.001) high percent inhibition of serum IgG from SLE patients with modified antigen. Chronic inflammation with excessive oxidative stress in SLE patients could be a possible reason for structural alterations in blood proteins, generating highly immunogenic unique new-epitopes. These in turn induce the generation of specific autoantibodies against G-HSA that may serve as a potential biomarker for SLE pathogenesis.

Comprehensive overview of human serum albumin glycation in diabetes mellitus.

The presence of excess glucose in blood is regarded as a sweet hurt for patients with diabetes. Human serum albumin (HSA) is the most abundant protein in human plasma, which undergoes severe non-enzymatic glycation with glucose in patients with diabetes; this modifies the structure and function of HSA. Furthermore, the advanced glycation end products produced by glycated HSA can cause pathological damage to the human body through various signaling pathways, eventually leading to complications of diabetes. Many potential glycation sites on HSA have different degrees of sensitivity to glucose concentration. This review provides a comprehensive assessment of the in vivo glycation sites of HSA; it also discusses the effects of glycation on the structure and function of HSA. Moreover, it addresses the relationship between HSA glycation and diabetes complications. Finally, it focuses on the value of non-enzymatic glycation of HSA in diabetes-related clinical applications.