Amide Region Research Articles

Application of Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy in Human Sera: Validate the method for contributing effective strategy for the storage and preservation

The serum is one of the biological specimens that have been extensively studied as biomarkers and is recognized as an effective tool for screening and diagnosing a variety of diseases. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) is a practical technique utilized in investigating characteristic spectra in infectious diseases cancer, and metabolic status. However, the pre-analytical procedure as storage condition is a crucial phase that directly impacts the accuracy of the result. In this study, we intend to investigate the effects of serum stabilization under both identical and distinct storage conditions on the FTIR spectral patterns, intensity variations, and macromolecule composition. The ten serum samples were stored in 3 different conditions including 4 °C, −20°C, and −80°C for six different time intervals (7, 14, 21, 28, 56, and 84 days). The spectra were obtained by ATR-FTIR spectroscopy. The serum stabilization was studied in two investigations: one focusing on the stability of serum under identical conditions over six different time intervals, and the other examining the stability of serum stored under three distinct conditions. Principal Component Analysis (PCA) and Area Under the Peak (AUP) were used to investigate clusters in different sets of data across five spectral ranges. The macromolecule composition was identified in conjunction with the intensity measurements. The results showed that the same conditions remained stable across six different time intervals, as indicated by the consistent PCA results. In contrast, the stabilization of serum under different temperature condition showed different major intensities across the five selected positive bands, including 1781 cm−1, 1740 cm−1 1727 cm−1 corresponding to lipid region (1800–1700 cm−1), and Amide region (1700 −1500 cm−1) at 1646 cm−1, and 1632 cm−1, when the serum was stored over 28 days. This might involve lipid peroxidation-induced changes in the secondary structure of proteins. Our findings indicated that serum should be stored at −80°C to ensure stabilization and achieve the highest intensity. Additionally, preserving serum under consistent conditions was crucial to minimize variability and prevent external factors from affecting the results.

Modifying physicochemical properties, rheology, and creaming stability of milk fat globule and membrane through ultrasound treatment

The healthy benefits of milk fat globules and membrane (MFGs/MFGM) ingredients are increasingly recognized in the dairy industry. In this research, we examined the effects of ultrasonic treatment on the physicochemical and rheological properties, as well as the emulsions stability of MFGs/MFGM derived from bovine raw milk. Fresh milk was subjected to sonication at frequencies of 20 kHz and 40 kHz, either individually or simultaneously, for durations of 5 min or 15 min, using work/rest cycles of 5 s on and 3 s off. Bovine milk, without any treatment, served as the control. Regardless of the intensity difference, ultrasonic treatment for 5 min resulted in more pronounced changes in the regions of Amide Ⅱ (1600–1500 cm−1), Amide Ⅲ (1500–1200 cm−1), and fingerprint region (1200–1900 cm−1) compared to both the 15 min treatments and control MFGs/MFGM. Principal component analysis (PCA) conducted on the entire spectra, as well as in the regions of Amide Ⅰ, Amide Ⅱ, and the fingerprint spectra, clustered the 5 min treatment distinctly from the control and MFGs/MFGM ultrasonically treated for 15 min. MFGs/MFGM samples following 20 kHz and 40 kHz synchronous treatment for 15 min exhibited lower absorbance bands at 1727–1726 cm−1, whereas a higher content at 1740 cm−1 was observed compared to control MFGs/MFGM. Additionally, a more significant reduction in the intramolecular β-sheet content in 20 + 40 kHz/ 15 min treatment was observed. According to the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) patterns, a diminished intensity of Periodic Acid Schiff 6/7 (PAS 6/7) bands was observed across all the MFGs/MFGM. Ultrasonic treatment retained more caseins while reducing the β –LG levels compared to the controls, enhancing the stability of MFGs/MFGM, except in MFGs/ MFGM subjected to 20 and 40 kHz simultaneously treated for 15 min. The irregular sphericity of fat globules was noted particularly in MFGs/MFGM treated at 20 kHz independently or in combination with 40 kHz for 15 min. According to the confocal laser scanning microscopy (CLSM), ultrasonic treatment facilitated the binding of caseins or whey proteins to the MFGs surface and induced flocculation of membrane proteins. Hierarchical cluster analysis (HCA) heat map further underscored the impact of ultrasonic treatments on the structural and compositional changes, as well as rheology and emulsions stability, of MFGs/MFGM.

Promotion of aromatic amino acids of extracellular polymeric substance targeted transformation via sulfite mediated iron redox cycling in sludge solid-liquid separation

Highly hydrophilic extracellular polymeric substance (EPS) with gel-like structure seriously plagues the development of sludge deep dewatering. Oxysulfur radicals-based oxidation driven by iron-bearing mineral proposes a promising strategy for effective EPS decomposition. However, the transformation and involved interaction mechanisms of aromatic proteins are still controversial due to the complex EPS structure. Herein, sulfite mediated siderite (denoted as Fe(II)/S(IV)) was developed for targeted transformation aromatic amino acids in EPS oxidation to strengthen sludge solid-liquid separation. The enhanced sludge dewaterability were benefited from the Fe(II)/S(IV) bonded interaction assisted by Fe3+/Fe2+ as redox interface that facilitating the release of intracellular bound water via diminish the hydrophily and bind strength with solid protons. The amide region nitrogen of aromatic amino acids (especially tyrosine and tryptophan) originating from EPS presented looser structure and lower spatial site resistance, which were attributed to the exposure of hydrophobic sites in amino groups after Fe(II)/S(IV) treatment. Furthermore, the effective decline of aromatic amino acids in inner layer-EPS (loosely bound EPS and tightly bound EPS) was directed from Fe-N targeted interaction by triggering a series of sulfate-based radical chain reactions. The good correlation between electron transfer amount (R2 = 0.926) and Fe-N (R2 = 0.925) with bonding interaction demonstrated that the complexation of aromatic amino acids with Fe sites on siderite/sulfite via Fe-N bonds, accounting for efficient sludge solid-liquid separation. This study deepens the understanding of sludge organic matter targeted transformation and provides a tactic for iron-based conditioning of sludge.

Dimeric and monomeric conformation of SARS-CoV-2 main protease: New technical approaches based on IR radiation

The main proteases Mpro are a group of highly conserved cysteine hydrolases in β-coronaviruses. They have been demonstrated to play an unavoidable role in viral replication, and consequently they have been suggested as key targets for treating coronavirus-caused infectious diseases, mainly from the COVID-19 epidemic. Since the most functional form for Mpro enzymatic activity is associated to its homodimer, compounds inhibiting dimerization should also inhibit catalytic activity. We show how PIR-SEIRA (Plasmonic Internal Reflection-Surface Enhanced InfraRed Absorption) spectroscopy can be a noteworthy technique to study proteins subtle structural variations associated to inhibitor binding. Nanoantennas arrays can selectively confine and enhance electromagnetic field via localized plasmonic resonances, thus promoting ultrasensitive detection of biomolecules in close proximity of nanoantenna arrays and enabling the effective investigation of protein monolayers. By adopting this approach, reflection measurements conducted under back illumination of nanoantennas allow to probe anchored protein monolayers, with minimum contribution of environmental buffer molecules. PIR-SEIRA spectroscopy on Mpro was carried out by ad hoc designed devices, resonating in the spectral region of Amide I and Amide II bands. We evaluated here the structure of anchored monomers and dimers in different buffered environment and in presence of a newly designed Mpro inhibitor. Experimental results show that dimerization is not associated to relevant backbone rearrangements of the protein at secondary structure level, and even if the compound inhibits the dimerization, it is not effective at breaking preformed dimers.

Structural changes in amide I and amide II regions of PCOS women analyzed by ATR-FTIR spectroscopy

The etiology of PCOS is complex and frequently mis or undiagnosed, which may enhance morbidity and reduce the quality of life. Attenuated total reflection- Fourier transform infrared (ATR-FTIR) spectroscopy examines the structural fingerprints of the biochemical compounds and can provide distinct FTIR spectra of the PCOS cases and controls. The present study recruited 61 PCOS cases and 38 control women. The student's t-test was used to compare BMI, WHR, and lipid profile. The FTIR spectral region was compared among both groups using the Mann-Whitney U test and multivariate analysis involved principal component analysis (PCA) and hierarchical cluster analysis (HCA). FTIR spectra of different phenotypes of PCOS were also analyzed using multivariate analysis. In univariate analysis, PCOS women had significantly higher WHR (p = 0.007), BMI (p = 0.04), triglycerides (p = 0.04), and VLDL (p = 0.02) than the controls. The spectral regions of amide I (1700-1600 cm-1) and amide II (1580-1480 cm-1), were significantly greater in the PCOS group than in the controls (p < 0.01 and p < 0.001, respectively). The PCA and HCA revealed a distinct molecular fingerprint for phenotype A (PCOM + OA + HA) and phenotype B (HA + OA).Our study postulated that the spectral regions of amide I and amide II can distinguish between PCOS cases and control women and it may be used for the diagnosis of cases.

Attenuated-total-reflection Fourier-transformed spectroscopy as a rapid tool to reveal the molecular structure of insect powders as ingredients for animal feeds

Abstract Unsustainable agriculture contributes to disastrous global effects – insect-based feed shows potential due to their sustainable, nutritional, and waste upcycling properties. Current EU legislation restricts insect-based meals to fish, pork, and poultry feed; but the near-future shows a great potential for wider acceptance in livestock feed. Black soldier fly larvae (BSFL), mealworm (MW), field cricket (FC), and banded cricket (BC) were sourced within three consecutive weeks – each batch was prepared, freeze-dried, then milled, and stored at −20 °C. Chemical composition of whole-insect meals was analysed for ether extract (EE), crude ash, and nitrogenic contents using standard wet chemistry protocols. Monogastric in vitro digestibility was determined through replicating gastric and full intestinal digestion; during this, R-amino acid content was determined through protein hydrolysis kinetics. Additionally, ATR-FTIR was used for molecular analysis, including identification of nutrient-associated functional spectral bands – structural differences were compared through principal component analysis. Insect-based ATR-FTIR analysis demonstrates notable differences in Amide regions, suggesting distinct protein secondary structures, but overall, FC and BC contain the highest crude protein (CP) levels. The lowest CP content was in BSFL; however, BSFL contained the highest ash content – likely consequence of high calcium. Dry matter (DM) yielded lowest in the crickets (FC-28.6; BC-26.9 g/100 g), and highest in MW-38.5 g/100 g; the sum of CP + EE in MW represented &gt;80% DM, but with higher EE contents-CP: EE = 2.45. Data shows greater chitin content in crickets than BSFL + MW. Crickets showed greater neutral detergent fibre (NDF) than BSFL + MW; however, acid-detergent fibre (ADF) was similar among all species, suggesting NDF may include amalgams of interlinked nutrients released by acid digestion. This first study shows for the first time evidence that rearing conditions and substrates influences molecular structure. Exponential solubilisation was observed during pepsin + pancreatin digestion for all, but BSFL exhibited the highest degree-of-hydrolysis during the pancreatin phase, surpassing others. Analysis indicates protein hydrolysis differences are linked to trypsin activity susceptibility.

Synthesis, Spectroscopic Evaluations and UV-Vis Titration Studies of New Symmetrical Amide Compounds Derived from N-6-[(4-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic Acid Methyl Ester

In this study, 2 flexible and pre-organized tetraamide compounds derived from N-6-[(4-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic acid methyl ester namely 1,2-bis[N,N’-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]pentane (L1) and 1,2-bis[N,N’-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]hexane (L2) have been successfully synthesized when reacted with diamines in 1:2 ratio. These new compounds were built from combination of 3 main components, as a trend requires for anion receptor which are (i) 2,6-pyridine dicarboxamide moieties as targeted anion binding host, (ii) amino methyl pyridine pendants arms as the flexible moieties and (iii) pentyl (-C5H10-) and hexyl (-C6H12-) unit as the spacer. Compounds L1-L2 were fully characterized by using elemental analyzer, Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectroscopy (GC-MS), 1H, 2D NOESY and 13C Nuclear Magnetic Resonance (NMR) spectroscopies, and Ultraviolet-visible (UV-Vis) spectroscopies. In this study, anion titration methods were used to identify the affinity towards selected anions. The results showed that L1 (having a pentyl spacer) had the highest affinity towards phosphate anions as compared to L2, where the red shift changes were observed in the UV-vis spectrum at the amide region. HIGHLIGHTS Two novel amide compounds with flexible and pre-organized structure are designed for use as potential anion receptors The flexible moieties at the amide and the linker allow hydrogen bonding interaction of the molecules with variety anions with different geometries Anion titration studies revealed good affinities towards phosphate anions as suggested in Hofmeister trend GRAPHICAL ABSTRACT

α-Synuclein Drives Tau's Cytotoxic Aggregates Formation through Hydrophobic Interactions.

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide 71 VTGVTAVAQKTV82 induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides 275 VQIINK280 and 306 VQIVYK311 through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

High pressure processing of whole soymilk: Effect on allergenicity, anti-nutritional factor, lipoxygenase activity and E-nose-aroma characteristics

Soymilk was subjected to high pressure processing (HPP) at different pressure levels (300–600 MPa) and time (5, 15 and 25 min) intervals. After the HPP treatment, a mild reduction was observed in soymilk pH and conductivity values; however, a sudden surge in the protein content (17.34±0.10 mg/ml) was recorded at 600 MPa (5 min) treatment. When soymilk proteins were evaluated for their structural changes, FTIR (amide regions), CD spectra, and UV inflorescence showed the positive responses and as the result, soy Kunitz trypsin inhibitor (SKTI) antigen binding ability reduced from 100% to 44.39±8.50% at 300 MPa (5 min). However, prolong exposure at 300 MPa had a negative effect on allergenicity. Nevertheless, HPP treatment reduced the lipoxygenase (100.00% to 68.13±12.80%) and trypsin inhibitor (100.00% to 91.30±1.45%) activities. In addition, the treatment also slightly altered the viscosity, whiteness, and volatile aroma components of soymilk after HPP treatment. Principal component analysis revealed that among 22 selected volatiles, only those belong to PC1 and PC2 caused 68% variance in aroma changes. Overall, HPP treatment reduced allergenicity, trypsin inhibitor activity and lipoxygenase activity without modifying the soymilk nature. Further, it also reduced the beany flavor inducing hexanal volatile content after the treatment.

Nutritional, biological, and structural properties of bioactive peptides from bellflower, Persian-willow, and bitter-orange pollens.

In this study, the composition of amino acids, nutritional characteristics, degree of hydrolysis (DH), antioxidant properties, and antibacterial activity of proteins and hydrolysates of bellflower (Campanula latifolia), Persian willow (Salix aegyptiaca), and bitter orange (Citrus aurantium L.) were investigated under the influence of different proteases (Alcalase: Al, trypsin: Tr, pancreatin: Pa, and pepsin: Pe). Evaluation of the structural features of the proteins showed amide regions (amide A, B, I-III) and secondary structures. Hydrophobic amino acids (∼38%), antioxidants (∼21%), and essential types (∼46%) form a significant part of the structure of flower pollen. The digestibility and nutritional quality (PER) of the hydrolyzed samples (CP: 1.67; CA: 1.89, and PW: 1.93) were more than the original protein. Among proteins and peptides, the highest degree of hydrolysis (34.6%: Al-PWH), inhibition of free radicals DPPH (84.2%: Al-CPH), ABTS (95.2%: Pa-CPH), OH (86.7%: Tr-CAH), NO (57.8%: Al-CPH), reducing power (1.31: Pa-CPH), total antioxidant activity (1.46: Pa-CPH), and chelation of iron ions (80%: Al-CPH and Al-CAH) and copper (50.3%: Pa-CAH) were affected by protein type, enzyme type, and amino acid composition. Also, the highest inhibition of the growth of Escherichia coli (25 mm) and Bacillus cereus (24 mm) were related to CP and PW hydrolysates, respectively. The results of this research showed that hydrolyzed flower pollens can be used as a rich source of essential amino acids as well as natural antioxidants and antibacterial in food and dietary products. PRACTICAL APPLICATION: Enzymatic hydrolysis of Campanula latifolia, Persian willow, and Citrus aurantium pollen proteins was performed. The hydrolyzed ones had high nutritional quality and digestibility (essential amino acids and PER index). Antioxidant properties and chelation of metal ions of peptides were affected by the type of protein and enzyme. The hydrolysates showed inhibitory activity against the growth of Esherichia coli and Bacillus cereus.

Studies of Thyroid Hormones (Propylthiouracil and L-Thyroxine) Interaction with Human Serum Albumin-Spectroscopic Approach

In this work, UV-absorption, fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to investigate the relationship between Propylthiouracil and L-Thyroxine with human serum albumin. The binding constants of propylthiouracil and L-Thyroxine have been determined of both UV-absorption and fluorescence spectroscopy. The binding Constants values measured at 293k are 1.659×10³ M^-1 for propylthiouracil and 1.013×10⁴ M^-1 for L-Thyroxine. The constant values of the Stern–Volmer quenching were determined to be 2.144×10³ L mol^-1 for propylthiouracil and 1.937×10³ L mol^-1 L-for Thyroxine. The UV-absorption intensity of HSA- hormones complexes has increased with increasing of propylthiouracil and L-Thyroxine concentration. With the rise in propylthiouracil and L-thyroxine concentrations, the fluorescence results indicate a decrease in HSA- hormone emission intensity. To determine the effects of protein secondary structure and hormone binding mechanisms, we have used FTIR spectroscopy with Fourier self-deconvolution technique and second derivative resolution enhancement, as well as curve-fitting methods for the investigation of the amide I, II, and III regions. The peak positions within the three amide regions (amide I, amide II and amide III) were allocated and any results were explored due to changes in concentration. Due to variations in hormone concentrations, the measurements of the FTIR spectra indicate a difference in the intensity of absorption bands.. FTIR Spectra measurements reflect a difference in the strength of the absorption bands due to changes in hormone concentrations.

High-throughput infrared spectroscopy for quantification of peptides in drug discovery

Peptides have gained an increasing importance in drug discovery as potential therapeutics. Discovery efforts toward finding new, efficacious peptide-based therapeutics have increased the throughput of peptide development, allowing the rapid generation of unique and pure peptide samples. However, high-throughput analysis of peptides may be still challenging and can encumber a high-throughput drug discovery campaign. We report herein a fit-for-purpose method to quantify peptide concentrations using high-throughput infrared spectroscopy (HT-IR). Through the development of this method, multiple critical method parameters were optimized including solvent composition, droplet deposition size, plate drying procedures, sample concentration, and internal standard. The relative absorbance of the amide region (1600–1750 cm-1) to the internal standard, K3Fe(CN)6 (2140 cm-1), was determined to be most effective at providing lowest interference for measuring peptide concentration. The best sample deposition was achieved by dissolving samples in a 50:50 v/v allyl alcohol/water mixture. The developed method was used on 96-well plates and analyzed at a rate of 22 min per plate. Calibration curves to measure sample concentration versus response relationship displayed sufficient linearity (R2 > 0.95). The repeatability and scope of detection was demonstrated with eighteen peptide samples that were measured with most values below 20% relative standard deviation. The linear dynamic range of the method was determined to be between 1 and 5 mg/mL. This developed HT-IR methodology could be a useful tool in peptide drug candidate lead identification and optimization processes.

Culture of rat mesenchymal stem cells on PHBV-PCL scaffolds: analysis of conditioned culture medium by FT-Raman spectroscopy.

Mesenchymal stem cells (MSCs) have great potential for application in cell therapy and tissue engineering procedures because of their plasticity and capacity to differentiate into different cell types. Given the widespread use of MSCs, it is necessary to better understand some properties related to osteogenic differentiation, particularly those linked to biomaterials used in tissue engineering. The aim of this study was to develop an analysis method using FT-Raman spectroscopy for the identification and quantification of biochemical components present in conditioned culture media derived from MSCs with or without induction of osteogenic differentiation. All experiments were performed between passages 3 and 5. For this analysis, MSCs were cultured on scaffolds composed of bioresorbable poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) polymers. MSCs (GIBCO®) were inoculated onto the pure polymers and 75:25 PHBV/PCL blend (dense and porous samples). The plate itself was used as control. The cells were maintained in DMEM (with low glucose) containing GlutaMAX® and 10% FBS at 37oC with 5% CO2 for 21 days. The conditioned culture media were collected and analyzed to probe for functional groups, as well as possible molecular variations associated with cell differentiation and metabolism. The method permitted to identify functional groups of specific molecules in the conditioned medium such as cholesterol, phosphatidylinositol, triglycerides, beta-subunit polypeptides, amide regions and hydrogen bonds of proteins, in addition to DNA expression. In the present study, FT-Raman spectroscopy exhibited limited resolution since different molecules can express similar or even the same stretching vibrations, a fact that makes analysis difficult. There were no variations in the readings between the samples studied. In conclusion, FT-Raman spectroscopy did not meet expectations under the conditions studied.

Biochemical and Mechanical Analysis of Occlusal and Proximal Carious Lesions.

A precise evaluation of caries excavation endpoint is essential in clinical and laboratory investigations. Caries invasion differentiates dentin into structurally altered layers. This study assessed these changes using Raman spectroscopy and Vickers microhardness. Ten permanent molars with occlusal and proximal carious lesions were assessed and compared at 130 points utilizing four Raman spectroscopic peaks: phosphate v1 at 960 cm-1, amide I (1650 cm-1), amide III (1235 cm-1) and the C-H bond of the pyrrolidine ring (1450 cm-1). The phosphate-to-amide I peak ratio and collagen integrity peak ratio (amide III: C-H bond) of carious zones were calculated and compared in both lesions. The former ratio was correlated to 130 Vickers microhardness indentations through lesions. The caries-infected dentin (CID) exhibited low phosphate peak, but higher amide I, III and C-H bond peaks than other zones in both lesions. The peaks in amide regions (I and III) varied in occlusal versus proximal lesions. A high correlation was found between mineral: matrix peak ratio and equivalent microhardness number within carious lesions, while the collagen integrity peak ratio was applied in proximal lesions only. Raman spectroscopy detected changes in the mineral and matrix contents within different carious zones and regions.

Modification of Whey Proteins by Sonication and Hydrolysis for the Emulsification and Spray Drying Encapsulation of Grape Seed Oil

In this study, whey protein concentrate (WPC) was sonicated or partially hydrolyzed by Alcalase, then examined as an emulsifier and carrier for the emulsification and spray drying of grape seed oil (GSO)-in-water emulsions. The modification treatments increased the free amino acid content and antioxidant activity (against DPPH and ABTS free radicals), as well as, the solubility, emulsifying, and foaming activities of WPC. The modified WPC-stabilized emulsions had smaller, more homogeneous droplets and a higher zeta potential as compared to intact WPC. The corresponding spray-dried powders also showed improved encapsulation efficiency, oxidative stability, reconstitution ability, flowability, solubility, and hygroscopicity. The morphology of particles obtained from the primary WPC (matrix type, irregular with surface pores) and modified WPC (reservoir type, wrinkled with surface indentations), as well as the oxidative stability of the GSO were influenced by the functional characteristics and antioxidant activity of the carriers. Changes in the secondary structures and amide regions of WPC, as well as the embedding of GSO in its matrix, were deduced from FTIR spectra after modifications. Partial enzymolysis had better results than ultrasonication; hence, the WPC hydrolysates are recommended as emulsifiers, carriers, and antioxidants for the delivery and protection of bioactive compounds.

Spray-drying to improve the functionality of amaranth protein via ultrasonic-assisted Maillard conjugation with red seaweed polysaccharide

Maillard conjugation has gained attention for its application in improving functional-properties of different plant proteins, including solubility and emulsification. Amaranth, a plant protein showing a higher lysine-content essential for conjugation, was conjugated with Gracilaria secundata polysaccharide via ultrasonic-assisted Maillard-conjugation. Post-ultrasonication, the outcomes from spray-drying as an alternative to freeze-drying were investigated. The comparison was based on conjugation-degree, solubility, water-or-oil holding capacity, and secondary structural changes in proteins. The protein: polysaccharide (w/w) of 1:1 and 2:1 displayed better conjugation, improved functional and structural aspects including the changes in the amide regions, oil-and-water holding capacity of the protein. Lower degree of conjugation, structural and functional changes for 1:2 samples can be the result of higher polysaccharide content leading to a shielding-effect over the reaction terminals of proteins. A significant difference between the properties was observed with different drying methods. Except for similar conjugation efficiency, the freeze-dried samples exhibited better oil-holding capacity, while the spray-dried samples performed better in water-holding capacity. The difference between spray-drying and freeze-drying could be due to the temperature difference resulting in protein denaturation, or the advancement of Maillard reaction. We demonstrated that spray-drying could be utilized as an alternative to freeze-drying step during ultrasonic-assisted Maillard conjugation, although a focus on optimization of conjugation and spray-drying parameters is required.

Synchrotron Fourier-Transform Infrared Microspectroscopy: Characterization of in vitro polarized tumor-associated macrophages stimulated by the secretome of inflammatory and non-inflammatory breast cancer cells

Studies suggested that the pathogenesis of inflammatory breast cancer (IBC) is related to inflammatory manifestations accompanied by specific cellular and molecular mechanisms in the IBC tumor microenvironment (TME). IBC is characterized by significantly higher infiltration of tumor-associated macrophages (TAMs) that contribute to its metastatic process via secreting many cytokines such as TNF, IL-6, IL-8, and IL-10 that enhance invasion and angiogenesis. Thus, there is a need to first understand how IBC-TME modulates the polarization of TAMs to better understand the role of TAMs in IBC. Herein, we used gene expression signature and Synchrotron Fourier-Transform Infrared Microspectroscopy (SR-μFTIR) to study the molecular and biochemical changes, respectively of in vitro polarized TAMs stimulated by the secretome of IBC and non-IBC cells. The gene expression signature showed significant differences in the macrophage's polarization-related genes between stimulated TAMs. FTIR spectra showed absorption bands in the region of 1700–1500 cm−1 attributed to the amide I ν(C=O), & νAS (CN), δ (NH), and amide II ν(CN), δ (NH) proteins bands. Moreover, three peaks of different intensities and areas were detected in the lipid region of the νCH2 and νCH3 stretching modes positioned within the 3000–2800 cm−1 range. The PCA analysis for the second derivative spectra of the amide regions discriminates between stimulated IBC and non-IBC TAMs. This study showed that IBC and non-IBC TMEs differentially modulate the polarization of TAMs and SR-μFTIR can determine these biochemical changes which will help to better understand the potential role of TAMs in IBC.

Effect of low‐temperature plasma treatment on the microbial inactivation and physicochemical properties of the oat grain

AbstractBackground and ObjectivesNaked oat grain is easily contaminated by microorganisms, and it needs pretreatment to extend its shelf life. Low‐temperature plasma treatment (LTPT) has the advantages of less energy consumption, safety, and convenience, and its applications in grain include microbial inactivation and flour modification. Therefore, we studied the changes in oat microbes and the physicochemical properties of oats at different plasma treatment times (0, 5, 10, 15, and 20 min at an output discharge voltage of 60 kV).FindingsThe results demonstrated that LTPT significantly decreased the number of microorganisms with the increase in treatment time, especially at 20 min. LTPT increased the L* and b* values and decreased the a* value of oat flour. Proper treatment time (5–10 min) did not affect the germination rate of the grain. Compared to the control sample, LTPT increased the water‐binding capacity and swelling power of flour and decreased the peak viscosity, final viscosity, and setback value. However, LTPT did not change the crystal structure. Besides, by fitting the peak of the amide region in Fourier transfer infrared analysis, it was found that the β‐sheet and α‐helix increased after treatment for 5–10 min.ConclusionsThese results indicated that LTPT (20 min) can effectively reduce the microbial count of oats and proper time treatment (5–10 min) can regulate the function of the flour and improve its quality.Significance and NoveltyLTPT as a new nonheat treatment technology can not only effectively reduce the microbial content of the grain but also improve the quality of the flour, which is a better pretreatment method for oat flour.

Spectroscopic investigation of tau protein conformational changes by static magnetic field exposure

Electromagnetic fields taint the molecular environment of proteins and induce changes in the central nervous system. This research applied Fourier transform infrared spectroscopic analysis to investigate the effects of static magnetic fields on tau protein in neurological disorders. It explores the conformational changes of tau protein and highlights its’ potential application as a pathological biomarker for early detection and therapeutic interventions. The results indicate that tau protein is susceptible to magnetic field exposure in the amide B, fingerprint, and amide regions (IV-VI). Changes in peak positions and band intensities were identified and delineated as the outcome effect of magnetic forces on molecular vibrations. Magnetic forces may affect the microtubule structure of the tau protein, leading to protein aggregation. These results indicate the potential application of FTIR spectroscopy for the early detection and classification of degenerative diseases through spectrum analysis. Different magnetic fields can be used as spontaneous therapeutic procedures to induce changes in the molecular environment of proteins.

Effect of bleaching and defatting treatment of camel skin on the color, structural and interfacial properties of extracted gelatin

The effect of defatting and bleaching of camel skin on gel-forming, structural, and interfacial properties of extracted gelatin was studied. Gelatin defatted for 6 h and bleached for 48 h (48BD-6 h) gave the highest yield (28.44%) while gelatin bleached for 24 h (24 BC) gave the highest gel strength (423.3 g). Electrophoretic analysis showed that all gelatin samples had α-chains as the predominant protein type. Fourier transformation infrared (FTIR) spectroscopy showed that all gelatin samples possessed major peaks in the amide region with reduced peak intensity recorded in defatted and bleached samples because of the loss of the triple helix state of the gelatin. X-ray diffraction analysis indicated that all the gelatin samples are basically amorphous with both weak and sharp peaks observed around 7° and broad peaks at ~19–22°. Microstructural analysis revealed highly cross-linked network with less voids in all the gelatin samples which correlated with high gel strength recorded. Colour of the gelatin powder samples were significantly improved by bleaching with an increase in the L ∗ -value and decrease in the a ∗ -value. These results indicates that with bleaching, gelatin molecules were oxidized, resulting in the production of gelatin cross-links, giving gelatin an improved gel strength, colour, and functionality. • Bleached and defatted camel skin produced gelatin with light color and improved interfacial properties. • Bleaching of camel skin produced gelatin with highest gel strength (423 g). • Camel skin gelatin with better functionality could be produced by defatting and bleaching pre-treatment.