Quantitative Determination Of Proteins Research Articles

Influence of resveratrol on the sorption of phosphorylated tau protein and MAPT on the PVDF membrane in a mouse model of Alzheimer’s disease

Alzheimer’s disease is a complex neurodegenerative disease based on various processes associated with the accumulation and aggregation of defective proteins. Among them, the particularly important ones are the following: amyloid-β, which is formed by the breakdown of amyloid precursor protein, the accumulation of hyperphosphorylated tau proteins inside neurons that form neurofibrillary tangles, and aberrant aggregation and inclusion formation of microtubule-associated protein tau (MAPT). APP/PS1 transgenic mice act as a model of Alzheimer’s disease and express mutant human genes that cause the accumulation of amyloid-β peptides in the brain. The goal of this work was a quantitative assessment of the level of p-tau231 in the brain of transgenic mice with a model of AD using the sorption method. The objectives of the study also included testing the ability of the natural polyphenol resveratrol to reduce the concentration of p-tau231 in the brain of transgenic mice and improve their cognitive functions. Western blot is a widely used method for the immunodetection and in vitro quantitative determination of proteins. Western blot allows separating proteins based on their molecular weight with the further transfer to an adsorption membrane. In this case, the proteins are transferred from the gel to the PVDF membrane using electrophoretic elution. This method involves placing a protein-containing polyacrylamide gel in direct contact with a PVDF membrane represented by a linear polymer with repetitive links -(CF2-CH2)-. Proteins transferred to the membrane are well-retained on its surface during the whole immunodetection process due to a combination of dipole and hydrophobic interactions. Western blot showed that mice with impaired protein aggregation accumulated significantly more MAPT and phosphorylated tau protein in the brain as compared to wild mice. In addition, in the course of the Morris water maze test, these mice showed cognitive deficits, which manifested both in the difficulty of finding the platform and more anxious behaviour, which confirmed pronounced thigmotaxis. The natural polyphenol resveratrol partially reversed cognitive deficits, although this effect was not associated with decreased levels of phosphorylated tau and MAPT.

Ion Moblity Mass Spectrometry in Multi-omics Studies

Mass spectrometry (MS) as an analytical technique enables the identification and quantitative determination of proteins, metabolites, or lipids in a studied sample. However, this method has limitations regarding the number of molecules that can be identified at a given time. To increase the number of identifications, the application of ion mobility spectrometry (IMS) can be employed. This technique allows the separation of ions based on their mobility while traversing the analyser in a gradient of an electromagnetic field and opposing gas pressure. The separation is performed in conjunction with MS analysis, adding another dimension to the analysis, resulting in a significant improvement in the number of identified compounds and a reduction in noise. Alternatively, while maintaining the same number of identifications, analysis can be performed in a shorter time period. It is crucial to pay special attention to the type of IMS analyser used, as its specific implementation dictates further stages of analysis and ion detection capabilities.

Development of a time-resolved immunochromatographic test strip for rapid and quantitative determination of retinol-binding protein 4 in urine.

Urine retinol-binding protein 4 (RBP4) has recently been reported as a novel earlier biomarker of chronic kidney disease (CKD) which is a global public health problem with high morbidity and mortality. Accurate and rapid detection of urine RBP4 is essential for early monitor of impaired kidney function and prevention of CKD progression. In the present study, we developed a time-resolved fluorescence immunochromatographic test strip (TRFIS) for the quantitative and rapid detection of urine RBP4. This TRFIS possessed excellent linearity ranging from 0.024 to 12.50 ng/mL for the detection of urine RBP4, and displayed a good linearity (Y = 239,581 × X + 617,238, R2 = 0.9902), with the lowest visual detection limit of 0.049 ng/mL. This TRFIS allows for quantitative detection of urine RBP4 within 15min and shows high specificity. The intra-batch coefficient of variation (CV) and the inter-batch CV were both < 8%, respectively. Additionally, this TRFIS was applied to detect RBP4 in the urine samples from healthy donors and patients with CKD, and the results of TRFIS could efficiently discern the patients with CKD from the healthy donors. Thedeveloped TRFIS has the characteristics of high sensitivity, high accuracy, and a wide linear range, and is suitable for rapid and quantitative determination of urine RBP4.

A rapid determination of wheat flours components based on near infrared spectroscopy and chemometrics

In this work, a rapid and simple analytical method for the quantitative determination of moisture, protein, wet gluten, starch and sedimentation index in the wheat flour was established by the combination of near infrared spectroscopy and chemometrics. The spectra of the 229 wheat flour samples were collected by a portable near infrared fast analyzer. The contents of these components were determined according to the relevant Chinese National Standards, and were taken as the corresponding reference database. Seven spectral pretreatment methods were employed to eliminate the optical interference from background and other noise information. The best result was obtained with FD+SG(15, 3)+MC method for moisture, protein, wet gluten and sedimentation index, FD+SG(15, 2)+MC method was more suitable for starch. The principal component numbers (PCs) were also optimized to obtain a superior model effect. Furthermore, partial least squares (PLS) and multiple linear regression (MLR) modeling methods were used to quantify the content of the components. When using FD+SG(15, 3)+MC pretreatment, all the PLS model parameters were significantly better than the MLR model. Both the predicted values and the reference values showed superior linear relationship within the calibration range. Moreover, the absolute error of the predicted values and their corresponding reference values in the PLS model were within their confidence intervals, respectively. The relative errors for moisture, protein, wet gluten and starch fluctuated little, only sedimentation index fluctuated greatly. The actual prediction correct rate of moisture, protein, wet gluten, starch and sedimentation index were 96.8%, 96.8%, 90.3%, 100.0% and 80.6%, respectively, which indicated the prediction was excellent.

Application of quantitative non-destructive determination of protein in wheat based on pretreatment combined with parallel convolutional neural network

With the increasing demand for wheat, the detection of wheat quality has become imperative. Protein content is an important indicator for wheat quality. Near infrared spectroscopy (NIRS) quantitative non-destructive testing technology has gained widespread application in agricultural field with the development of science and chemometrics technology. In this study, NIRS system was employed to measure the spectra of wheat, and the original spectra were pretreated using Savitzky-Golay smoothing (SG) pretreatment method. Subsequently, the NIRS prediction model of protein in wheat that using SG combined with parallel convolutional neural network (PaBATunNet) was established. PaBATunNet was composed of a one-dimensional convolutional layer, a parallel convolution module (Module), a flattening layer, four fully connected layers and a parameter regulator (PR). Module was made up of five submodules and a Concatenate function. The multidimensional features of the spectra were extracted by five submodules and spliced by Concatenate function. SG pretreatment combined with PaBATunNet (SG-PaBATunNet) was compared with commonly modeling methods, such as SG-partial least squares (SG-PLS), SG-principal component regression (SG-PCR), SG-support vector machine (SG-SVM) and SG-back propagation neural network (SG-BP). The results demonstrated that the modeling accuracy and prediction accuracy of SG-PaBATunNet were improved by 26.7%, 23.9%, 45.6%, 44.2%, and 38.4%, 39.6%, 60.1%, 58.0%, when compared with SG-PLS, SG-PCR, SG-SVM and SG-BP. The problems of low prediction accuracy and poor generalization ability with commonly modeling methods were effectively addressed by SG-PaBATunNet. This study provides an essential theoretical foundation for developing a fast, nondestructive and high-precision NIRS quantitative analysis model of protein in wheat.

An ultra-sensitive SPR immunosensor for quantitative determination of human cartilage oligomeric matrix protein biomarker

This paper reports the development of a novel surface plasmon resonance (SPR) immunosensor for ultra-sensitive quantitative determination of human articular cartilage oligomeric matrix protein (COMP), a major component of the extracellular matrix and an exploratory biomarker. Capture antibodies against human COMP (anti-COMP16F12) were covalently immobilized on an 11-mercaptoundecanoic acid (11-MUA) self-assembled monolayer (SAM)-coated SPR sensor disk and a dual sandwich-type signal amplification strategy using biotinylated detection antibodies against COMP (anti-COMP17C10-biot) and streptavidin-conjugated quantum dots (SAv‒QDs) were used for the development of an immunosensor. The binding of high-mass SAv‒QDs via biotin–streptavidin interaction to the surface of the immunosensor resulted in a drastic increase in the sensitivity. The developed immunosensor was able to detect concentrations of COMP in a range from 2.80 to 680.54 fM with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.15 and 0.50 fM, respectively. The immunosensor exhibited good repeatability (relative standard deviation (RSD) 8.05%) and reproducibility (RSD 9.88%) as well as excellent operational stability (2.14 % decrease in SPR signal after 13 days). In addition, the analysis of secretomes of human knee articular cartilage explants from patients with osteoarthritis revealed that the immunosensor has good accuracy (analytical error less than 5 %). These results indicate that the immunosensor developed may be suitable for quantitative determination of COMP derived from articular cartilage and other synovial joint tissues in clinical studies.

Stromal-vascular fraction of adipose tissue using in the repair of distal biceps tendon tears

Distal biceps tendon rupture is most commonly found in working-age men, making the treatment terms and functional recovery level of significant socio-economic importance. Modern scientific research aims to minimize the number of complications, particularly recurrent ruptures. Attention is drawn to modern technologies aimed at stimulating regenerative processes, including the use of the stromal vascular fraction (SVF) of abdominal adipose tissue. The article presents the results of the practical application of SVF in the surgical restoration of the distal biceps tendon of the shoulder. The aim of the study: to improve the results of surgical treatment of distal biceps tendon rupture, shorten recovery times and reduce the incidence of complications using stromal vascular fraction obtained from adipose tissue. Materials and methods. The study was carried out by evaluating the results of surgical restoration of the distal biceps tendon in 34 patients who were divided into 2 groups – with intraoperative introduction of SVF at the reattachment site (n = 14) and without it (n = 20). At follow-up examinations after 3 days, 2 weeks, 6 weeks, and 3 months, the results of the patients were evaluated using the VASH, DASH scales and the range of motion in the affected elbow joint was measured. In addition, a general blood analysis and quantitative determination of C-reactive protein were performed before the operation and at follow-up visits. Results. There was no difference in the level of C-reactive protein and the general blood analysis score between patients in both groups at all study time points. It was found that after 2 weeks, the VAS score was significantly lower in the study group. The DASH score on follow-up examinations after 2 and 6 weeks was significantly better in the study group. Also, at follow-up examinations after 2 and 6 weeks, a greater volume of supination movements was observed in the study group. Conclusions. The using of SVF did not lead to the development of postoperative complications. The using of SVF allowed the reduction of the recovery time and decreased in the incidence of complications, as well as improved functional outcomes.

Qualitative and quantitative determination of proteins in extracts of some medicinal plants

Introduction. Global consumption of plant protein is increasing and high-fiber plants have health benefits through valuable phytochemicals. Plant proteins serve as an alternative to animal proteins to meet consumer demand on the one hand and reduce the risk of disease on the other. Material and Methods. We performed qualitative and quantitative determination of proteins in extracts by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) and total content of proteins by Bradford assay. Results. Applied methods for the qualitative and quantitative determination of proteins in dry extracts of medicinal plants: Agrimonia eupatoria L., Cichorium intybus L., Galium verum L., and Solidago virgaurea L. confirm that proteins were detected in all dry extracts and were determined the total content of them. Conclusion. For all extracts obtained from aerial parts of: Agrimonia eupatoria, Cichorium intybus, Galium verum and Solidago virgaurea we find a low protein concentration, which implies minimizing allergic reactions and intolerance to the extracts studied.

Analysis of differential proteins between non-capacitated and capacitated boar sperm and verification of the effect of phosphofructokinase on capacitation

The objective of this study was to analyze the differences in the proteins in non-capacitated and capacitated boar sperm and to identify the functions of the differential proteins and key capacitation proteins of boar sperm before and after capacitation. Transwell chambers were used to separate capacitated sperm proteins using a unique polycarbonate membrane. Meanwhile, isotopic tags for relative and absolute quantification combined with LC‒MS/MS analysis were used for quantitative determination of differential proteins. Through the comparative analysis of different databases, 475 different proteins were identified in non-capacitated sperm and capacitated sperm, of which 303 were significantly upregulated and 172 were significantly downregulated. These differentially-expressed proteins are mainly involved in redox processes, cell biosynthesis processes and cell aromatic compound metabolism biological processes. They also participate in the signaling pathways of phosphorylation, ketone synthesis and degradation, most of which interact to varying degrees. Among these differentially-expressed proteins, phosphofructokinase attracted our attention as a potential capacitated protein. We further verified that phosphofructokinase can promote boar sperm capacitation by immunoblotting.

In Vitro and In Silico Evaluation of Indole-Bearing Squaraine Dyes as Potential Human Serum Albumin Fluorescent Probes

The quantitative determination of proteins is an important parameter in biochemistry, biotechnology and immunodiagnostics, and the importance of serum albumin in clinical diagnosis should be highlighted, given that alterations in its concentration are generally associated with certain diseases. As possible probes for this purpose, squaraine dyes have been arousing the interest of many researchers due to their unique properties, such as absorption in the visible spectra, moderate relative fluorescence quantum yields and increased fluorescence intensity after non-covalent binding to specific ligands. In this work, five squaraine dyes, four of which have never been reported in the literature, were characterized and evaluated in vitro and in silico concerning their potential application as fluorescent probes for human serum albumin detection. After interaction with the protein, the fluorescence intensity increased from 12 to 41 times, depending on the dye under study. High sensitivity (1.0 × 105–5.4 × 105 nM), low detection limits (168–352 nM) and moderate quantitation limits (560–1172 nM) were obtained, proving the efficiency of the method. In addition, moderate-to-excellent selectivity was observed compared to γ-globulin proteins. Molecular docking suggests that the dyes interact more effectively with the Sudlow site I, and binding energies have been markedly higher than those of warfarin, a molecule known to bind to this site specifically.

Cadmium selenide sulfide quantum dots with tuneable emission profiles: An electrochemiluminescence platform for the determination of TIMP-1 protein

The development of electrochemiluminescent (ECL) luminophores with tuneable emission profiles is a key requirement in the development of multi-analyte ECL sensing platforms. This study presents the first reported use of cadmium selenide sulfide (CdSeS) quantum dots (QDs) as ECL emitters in which both the ECL emission profile and cathodic potential can be tailored by alteration of the Se/S ratio. CdSeS QDs were synthesised using an aqueous synthetic route thereby avoiding the use of organic reagents, high temperatures and inert gasses. The suitability of the CdSeS QDs to ECL sensing applications is demonstrated via the quantitative determination of TIMP-1 protein at clinically relevant concentrations. The developed cathodic ECL immunosensor exhibited a detectable linear range of 6–60 ng/mL and a limit of detection (LOD) of 1.54 ng/mL. TIMP-1 protein plays a crucial role in pregnancy, wound healing, and cancer prognosis.

Quantitative Determination of Whey Protein to Casein Ratio in Infant Formula Milk Powder.

This study was aimed to establish a method for quantitatively determining the ratio of whey protein in the total protein of infant formula by respectively selecting two characteristic peptides from whey protein and casein and calculating the ratio between the characteristic peptides. A nanoliter high-performance liquid chromatography tandem high-resolution mass spectrometry (Q Exactive) was used to simultaneously detect the characteristic peptides of two main whey proteins and two main caseins. The characteristic peptides were calculated, predicted, and screened using the ExPASy website, and peptide information was confirmed by database retrieval after the analysis by using a high-resolution mass spectrometer. The matrix effect was compensated by comparing the characteristic peptides in whey protein with those in casein protein, in which isotope internal standards were not required. The influence of the changes of the protein content in whey protein and casein on the detection method was eliminated by the calculation formula designed by ourselves. In this detection method, the sample was stable in the total protein concentration range of between 0.1 and 0.4 mg/ml. In the simulated industrial processing environment, with desalted whey powder, the recovery rate was 98.63–113.33% under different spiked levels with good reproducibility (RSD<8%). The RSDs of intraday and interday precisions were 2.03–9.35% and 0.61–11.02%, respectively. The different processing procedures of samples had no significant impact on the detection of whey protein (RSD% for milk samples treated by different processing techniques was 2.97%). The quantitation method of whey protein was applied to evaluate the whey protein content in different brands of commercially available milk powder. In summary, the proposed method was applicable for quantitative analysis of whey proteins in the infant formula.

Prognostic model of early inflammation development in periodontal tissues by biochemical parameters of oral fluid in patients with orthodontic appliances

One of the main etiological risk factors and pathogenetic mechanisms for the development of inflammatory diseases of the periodontal disease is a bite pathology or dentofacial anomalies. Therefore, in recent years, scientists make attempts to find new markers that would allow to predict the course of the disease at the preclinical stage of its diagnostics, which would allow to take preventive treatment. In recent years, individual proteins of the mouth, which include matrix metalloproteinases (MMP-8), which can hydrolyze the main proteins in extracellular space and lactoferrin, catelitsidine, KLOTHO protein should be considered leading markers. The purpose is to predict the emergence of early inflammation in periodontal tissues in patients with non-removable orthodontic appliance by studying protein content in the oral fluid in the dynamics of treatment. Among the 113 patients surveyed by us, which underwent orthodontic treatment with non-removable appliance, according to clinical and laboratory studies, 82 people (72,57%) had signs of early inflammation of periodontal tissues. All exa­mined young people were students or students of educational institutions who appealed for advice and treatment to a dental clinic. Biochemical studies of oral fluid and their analysis was conducted at the beginning of orthodontic treatment and 3 and 6 months after the delivery of non-removable orthodontic appliance. The oral fluid was collected in the morning, and the quantitative determination of proteins in it was carried out by the IFA method. In order to assess the probability of prognostication of early inflammation in patients with orthodontic appliance, there was made rank correlation analysis with the determination of the correlation coefficients of the disparity (rs), ROC analysis with the deter­mination of Optimal Cut-Off Point (OСР) – the value of the indicator for prediction and simple and multiple logistic regressions with the calculation of the odds ratio and the construction of a prognostic model (logistics regression equation). For the analysis of factors, on the basis of which it is possible to predict early inflammation of periodontal tissues in patients with orthodontic appliance, a correlation analysis was performed, which showed that the largest changes were in the biochemical parameters of the mouth, namely: MMP-8 (rs=0.58; p&lt;0.001), lactoferin (rs=0.45; p&lt;0.001), catelitsidine (rs= -0.59; p&lt;0.001) and KLOTHO protein (rs= -0.58; p&lt;0.001), with which statistically significant correlations were established. ROC analysis was used to evaluate the discriminatory capacity of the markers investigated, which showed the presence of statistically significant correlations with early signs of inflammatory process in periodontal tissues. As a result of the correlation analysis, it has been found that the most significant changes in the inflammatory process in periodontal tissues were in the biochemical parameters of the mouth, such as MMP-8 (rs=0.58; p&amp;lt; 0.001), lactoferin (rs=0.45; p&amp;lt; 0.001), catholicidine (rs= -0.59; p&amp;lt; 0.001) and Klotho protein (rs= -0.58; p&amp;lt; 0.001), with which statistically significant correlations of average force were detected. The chances of patients with non-removable orthodontic appliance for the development of inflammation in the periodontal tissues are increased by 4. times.

Biochemical and Pathomorphological Investigations on Rabbits with Experimentally Induced Hepatic Eimeriosis

Abstract The present study aimed to evaluate the changes in concentrations of some biochemical parameters, as well as macro and microscopic alterations during Eimeria stiedae infection in rabbits. The experiment was performed using 12 three-month-old healthy rabbits, randomly allocated into 2 equal groups: G1 (controls, uninfected animals) and G2 (rabbits infected with E. stiedae). Blood samples were collected at time zero (prior to the infection), 6th, 24th, and 48th hours, and also 7th, 14th, 21st, 28th days after the infection. After sampling, the blood was centrifuged, plasma was separated and frozen at -20 ºC until analyzed. Thawed plasma was used for the quantitative determination of haptoglobin (Hp), total protein (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), total cholesterol (TC), total bilirubin (TBIL), urea, and creatinine (CREA). The results in infected rabbits revealed a significant increase in Hp, AST, ALT, GGT, TBIL, and TC levels, as well as a significant decrease in ALP and urea. A weak hyperproteinemia was also observed. There were no changes in CREA concentration. At the end of the clinical investigation, all rabbits were humanely euthanized and necropsied. The post-mortem examination of the infected group revealed hepatomegaly, multifocal yellowish nodules diffusely spread over the liver surface and in the parenchyma, considerably dilated bile ducts, and biliary hyperplasia. Given the results obtained from this experiment, it can be affirmed that hepatic eimeriosis in rabbits is a severe parasitic disease leading to significant disturbances of liver histology and resulting changes in the biochemical profile of infected rabbits.

Highly sensitive surface-enhanced Raman scattering-based immunosensor incorporating half antibody-fragment for quantitative detection of Alzheimer's disease biomarker in blood

Blood-based detection of Alzheimer's disease (AD) biomarker has become a prominent method for diagnosis of AD which can replace the complex and invasive cerebrospinal fluid (CSF)-based diagnostic method. However, the application of blood AD biomarker in actual AD diagnosis is hampered by the extremely low concentration of biomarkers in blood, as well as the existence of interfering proteins. Therefore, it is essential to develop a sensitive and specific detection platform to achieve blood-based diagnosis of AD. Here, a surface-enhanced Raman scattering (SERS)-based sensor is developed for the quantitative determination of tau protein in the plasma of AD patients. To acquire femtomolar-level detection limit, this platform involves the use of half antibody fragment immobilized onto head-flocked gold nanopillar SERS substrates and SERS-nanotags. The small size of the half antibody fragment maximizes the effect of plasmon coupling, by reducing the distance between SERS substrates and SERS-nanotags. Also, the use of half antibody fragment improves the antigen recognition ability by immobilizing the antibody with high density and efficient orientation of the antibody. The sensor using these characteristics showed a low detection limit of 3.21 fM and a wide detection range (10 fM - 1 μM). The platform was also able to accurately quantify the tau protein in the clinical plasma sample and correctly distinguish the AD patient from the healthy control. The ultrasensitive and specific SERS immunoassay platform facilitates accurate and early detection of AD biomarkers and can serve as a valuable tool for simple point-of-care testing in clinical diagnosis.

Evaluation of vitamin D and inflammatory markers in elderly

Vitamin D is an immune modulator, in addition to being interrelated with calcium homeostasis and bone metabolism. Recent studies have associated vitamin D with inflammatory processes. C-reactive protein (CRP), platelet/lymphocyte ratio (PLR) and neutrophil/lymphocyte ratio (NLR) have been used to determine inflammation. There is no consensus on the use of these markers to determine an association between inflammation and vitamin D levels. The objective of this study was to evaluate the association between inflammatory markers and vitamin D in the elderly. A cross-sectional, descriptive study was performed based on the analysis of vitamin D, CRP (quantitative determination of C-Reactive Protein by the ultra-sensitive method) and blood count of institutionalized elderly. In this study, 64% showed vitamin D deficiency, with mean value of 22 ng/mL. In the vitamin D deficient group, the mean values found were: CRP 4.5 mg/L; NLR 2.35 and PLR 119. In the group without vitamin D deficiency the mean values were: CRP 4 mg/L; NLR 1.87 and PLR 111 without statistical difference between the values of the analyzed parameters. The results point to a predominant profile of vitamin D deficiency in the evaluated individuals. No association was found between vitamin D values and the inflammatory markers analyzed.

A DNA Electrochemical Sensor via Terminal Protection of Small-Molecule-Linked DNA for Highly Sensitive Protein Detection.

The qualitative and quantitative determination of marker protein is of great significance in the life sciences and in medicine. Here, we developed an electrochemical DNA biosensor for protein detection based on DNA self-assembly and the terminal protecting effects of small-molecule-linked DNA. This strategy is demonstrated using the small molecule biotin and its receptor protein streptavidin (SA). We immobilized DNA with a designed structure and sequence on the surface of the gold electrode, and we named it M1-Biotin DNA. M1-Biotin DNA selectively combines with SA to generate M1-Biotin-SA DNA and protects M1-Biotin DNA from digestion by EXO III; therefore, M1-Biotin DNA remains intact on the electrode surface. M1-Biotin-SA DNA was modified with methylene blue (MB); the MB reporter molecule is located near the surface of the gold electrode, which generates a substantial electrochemical signal during the detection of SA. Through this strategy, we can exploit the presence or absence of an electrochemical signal to provide qualitative target protein determination as well as the strength of the electrochemical signal to quantitatively analyze the target protein concentration. This strategy has been proven to be used for the quantitative analysis of the interaction between biotin and streptavidin (SA). Under optimal conditions, the detection limit of the proposed biosensor is as low as 18.8 pM, and the linear range is from 0.5 nM to 5 μM, showing high sensitivity. The detection ability of this DNA biosensor in complex serum samples has also been studied. At the same time, we detected the folate receptor (FR) to confirm that this strategy can be used to detect other proteins. Therefore, this electrochemical DNA biosensor provides a sensitive, low-cost, and fast target protein detection platform, which may provide a reliable and powerful tool for early disease diagnosis.

Mass Spectrometry (MS/MS) and Proteomics: A High-Performance Bioanalytical Technique for the Peptide Drug Discovery

Drug discovery research focuses on the Rational Drug Design (RDD) concepts, and the major obstacles in the drug discovery process are the lack of target specificity and selectivity. The realization of higher target selectivity of peptide drugs has promoted peptide research. Rapid growth in genomics along with recombinant DNA (rDNA) technology and gene expression studies stimulated the peptide research. The promising use of peptide therapeutics demands sensitive and selective quantification methods. Protein sequencing and proteomic investigations can be successfully accomplished through the Mass Spectroscopy (MS) based methods. Mass spectroscopy-based soft ionization methods, namely, electrospray ionization (ESI) and Matrix-Assisted Laser Desorption/Ionization (MALDI), offer high-throughput sequencing to provide the characterization (sequence and structure) of intact proteins/peptides. The advent of tandem Mass Spectrometry (MS/MS) along with data acquisition methods are the basis for the evolution of peptide therapeutics research. The evolution of data science helped in developing computational proteomics, which assists in the quantitative determination of protein samples. This review narrates the role of mass spectrometry in the peptide drug discovery particularly in the sequence characterization along with the latest developments, such as computational proteomics.

Perspectives of Infrared Spectroscopy in Quantitative Estimation of Proteins

Background: Infrared (IR) spectroscopy is a well-established technique for the structural elucidation of simple as well complex molecules. It has wide applications in the qualitative as well as quantitative determination of proteins in different samples. It provides a clear picture of the primary, secondary, or tertiary structure of a protein. Infrared radiations are used to assess different vibrational modes arise from variations in the structural components of a protein. Methods: Various research reports were collected from search engines like Sciencedirect, Pubmed, Researchgate and Google Scholar. These were further studied thoroughly and important findings/data were compiled and represented with the help of tables and figures. The procured data which includes band width, frequency and intensity has been employed to elucidate the structure of a protein. Results: It was found from various reports that fourier transform infrared spectroscopy (FT-IR) has been widely utilized for prediction of secondary structure of protein in the past few years. FTIR has the ability to trace out various structural modifications in the protein structure which arise due to interactions with other materials. It is also evident it can be utilized to quantify the proteins in variety of samples. Conclusion: The present review describes the basic principle and the instrumentation of IR spectroscopy along with its advancements. Beyond this, various applications of this technique in determination of protein structure and quantification in different materials such as foods stuffs, biotechnological products and biological fluids have also been summarized.

FEATURES OF KIDNEY DAMAGE IN HIV-INFECTED

Relevance. In HIV-infected patients, renal disease, which is characterized by severe clinical manifestations, can significantly affect the prognosis of life. Given the growing number of HIV-infected people in the world and the increase in the life expectancy of such patients, an increase in the number of HIV-infected people in need of expensive renal replacement therapy, as well as kidney transplantation, should be expected. But the question of the nature of kidney damage in HIV infection in Ukraine is still insufficiently covered.&#x0D; The objective of the work is to establish the clinical and laboratory features of kidney damage in HIV infection.&#x0D; Materials and methods. 292 patients with HIV were examined. Screening for markers of kidney damage (albuminuria/proteinuria) was performed by test systems (using urine strips). The results obtained with the help of test strips were considered as indicative. In the presence of ≥1+ proteinuria in the screening test, which corresponded to a gradation of 30 mg/l, repeated urine analyzes were performed with quantitative determination of protein on a spectrophotometer, separated in time from 3 days to one week. The functional state of the kidneys was assessed by an integrated indicator that characterizes the degree of preservation/loss of mass of active nephrons. The criterion for renal impairment was a decrease in glomerular filtration rate (GFR) &lt;60 ml/min by 1.73 m2. Chronic kidney disease was diagnosed when proteinuria or proteinuria was detected in combination with a decrease in GFR for 3 months or more.&#x0D; Results. Based on the main markers of renal damage (persistent proteinuria (PU) and glomerular filtration rate &lt;60 ml/min/1.73m2), 48 people were diagnosed with chronic kidney disease, which was often accompanied by dysfunction of these organs. Based on the analysis of complaints, anamnestic data, and clinical symptoms of kidney damage, patients were divided into 2 groups. The first group (n = 31, or 64.6%) - patients with tubulointerstitial, the second group (n = 17, or 35.4%) - patients with glomerular diseases. Increased PU levels are accompanied by significantly significant renal impairment and a more frequent combination with hypertension and hematuria in the absence of significant differences in the frequency of opportunistic diseases.&#x0D; Conclusions. In HIV-infected kidney damage is most often characterized by their tubulointerstitial lesions. At the same time, glomerular kidney damage, which is much less common, is accompanied by significantly higher levels of HIV RNA.