Protein Secondary Structure Research Articles

Effect of Boiling Time on the Color, Water, Protein Secondary Structure, and Volatile Compounds of Beef

The influence of boiling time on the persistent changes in the surface color, water content and distribution, protein secondary structure, and the concentration of volatile compounds in beef were studied, in order to obtain quality short-term boiled beef slices. The results show that the water content of beef samples significantly decreased and migration occurred between the high-freedom water and the low-freedom water. On average, boiling for 1 min was a key point in the changes of color parameters (L*, a*, b*, w, ΔE, and BI) and partial protein secondary structure because of the change in the ambient temperature around beef. In six samples, 29 volatile compounds were confirmed by GC–MS, and 13 compounds were regarded as the potential key volatile compounds, including 1-heptanol, 1-octen-3-ol, octanal, hexanal, decanal, heptanal, nonanal, (E, E)-2,4-decadienal, (E, E)-2,4-nonadienal, dodecanal, (E)-2-undecenal, 2,3-octanedione, and 2-pentylfuran. The color, water, and protein secondary structure were closely correlated with some potential key volatile compounds. The results could be used to guide the consumers to better grasp the quality of hot-pot meat during gatherings and have a comfortable consumer experience.

Bamboo Leaf Protein Concentrate: Wet Fractionation, Protein Secondary Structure, Digestibility, Trypsin Inhibition

Bamboo Leaf Protein Concentrate: Wet Fractionation, Protein Secondary Structure, Digestibility, Trypsin Inhibition

Identification, Genomic Characterization, and Phylogenetic Relationship of the Heat Shock Protein Beta-1 (HSPB1) in Placental Mammals

Heat Shock Protein Beta-1 (HSPB1), a molecular chaperone crucial for cellular response and proteostasis, exhibits evolutionary conservation with potential lineage-specific adaptations in placental mammals, warranting detailed comparative genomic investigation. The study investigated the characteristics, evolutionary links, motifs, secondary structure, and genetic organization of the HSPB1 protein across twelve distinct mammals. Significant sequence conservation was identified using multiple sequence alignments (MSA), with over 70% identity in specific areas among the represented species. Physiochemical analysis revealed that all species’ protein sequences exhibited an acidic nature, while instability indices indicated inherent protein instability. The GRAVY analysis referred to hydrophilic properties, while the aliphatic index showed heat stability. Phylogenetic analysis revealed five distinct clades, corresponding to major placental mammals groups (e.g. Homo sapiens, Bos Taurus), which underscores deep evolutionary divergences and conserved stress-response adaptations across lineages. Motif analysis revealed distinctive patterns in several species, and InterProScan results revealed membership in the "Homologous superfamily HSP20_like_Chapserson" family. An examination of the genetic organization indicated differences among all the represented species in the upstream, downstream, intron, and CDS regions, and the presence of conserved regions suggested their identity and similarity matrices. The current study conducted a computational approach and supporting evidence that HSPB1 is a novel heat shock responsive protein identified in placental mammals. The current study findings provide a foundational framework delving into HSPB1 evolutionary and lineage-specific diversification, offering valuable insights into stress adaptation mechanisms and their implications for biomedical or evolutionary studies in mammals.

Tannic acid-mediated covalent effects on the structural and antioxidant properties of dual zein/casein protein complex nanoparticles.

Tannic acid-mediated covalent effects on the structural and antioxidant properties of dual zein/casein protein complex nanoparticles.

Unraveling the Impact of Diverse Salt Solvent Systems on the Structure and Functionality of Eggshell Membrane Proteins

ABSTRACTThis study investigated the effects of different solvent systems on the microstructure, roughness, and secondary structure of soluble eggshell membrane proteins (SEPs). The solvent system of CaCl2/C2H5OH/H2O produced tiny holes on the surface of SEP, and LiBr resulted in the formation of long holes. The saline solution increased the diameter of the protein fiber, the particle size of the solution, and the surface roughness of regenerated SEP films, mainly due to the enhanced intermolecular aggregation and precipitation. Zeta potential measurements indicated salts decreased the negative values and reduced the stability of the SEP solution. The different solutions showed similar circular dichroism waveforms. The peak intensity decreased at the positive and negative peaks, indicating that the triple helix structure of collagen was denatured to different degrees. Besides, the addition of salts decreased the content of α‐helices and the β‐turns and increased the content of β‐sheets and random coils, indicating an increase in the disordered structure of the protein. This study contributes to a deeper understanding of the structural and functional relationships of eggshell membrane proteins, providing a vital basis for developing novel, eco‐friendly, and multifunctional protein materials.

Mini-GRID therapy delivers optimised spatially fractionated radiation therapy using a flattening free filter accelerator

BackgroundRadioresistant tumours remain a challenge for conventional radiation therapy (RT), and often, only palliative treatment can be offered. Recently developed techniques, such as spatially fractionated radiation therapy (SFRT) could potentially improve treatment. However, current clinical SFRT implementations do not allow the full potential to be exploited. We further optimize SFRT, developing mini-GRID, which uses a flattening free filter accelerator.MethodsThe increase in normal tissue tolerances provided by mini-GRID compared to conventional RT and GRID therapy was validated in a rat model of brain irradiation in a longitudinal imaging study, behavioural tests and by histopathological evaluation.ResultsThe implementation optimizes mini-GRID therapy, with beam widths around 2 mm2. The peak-to-valley dose ratios and peak dose rates are around 4 and 7 Gy/min, respectively. Mini-GRID RT allows the use of high peak doses: 42 Gy in one fraction, a factor more than twice higher than the peak doses generally employed in conventional GRID therapy (20 Gy peak dose). This enables the use of more aggressive and potentially curative treatments. Infrared microspectroscopy analysis suggests different early biochemical changes in both modalities, with conventional RT leading to stronger modifications in the secondary protein structure, and higher oxidative damage than mini-GRID RT.ConclusionsThe possibility to treat both large and small tumours, and to perform safe and potentially curative dose escalations in previously untreatable cases, makes mini-GRID a promising approach to expand the clinical use of SFRT.

Enhancing the Digestibility and Functional Properties of Food Proteins Using Non‐Thermal Plasma

ABSTRACTFood proteins are key ingredients that enhance product texture while offering numerous health benefits and are essential for both structure and nutrition. The objective of the current study is to improve the bio‐ and techno‐functionalities of food proteins simultaneously through non‐thermal plasma exposure. Four different food proteins (pea, rice, wheat gluten, and milk proteins) were exposed to plasma at voltage 240 V, frequency 1.5 kHz, and 30 min exposure time. The structural, digestibility, bioactivity, and techno‐functional properties were analyzed. Plasma treatment alters the secondary structure of proteins by increasing β‐structures and random coils, while decreasing α‐helices, reducing surface hydrophobicity. The study demonstrated that prolonged treatment durations and elevated voltage intensities significantly enhance protein digestibility and increase amino acid release, with gluten showing the highest improvement in both digestibility and free amino acid content among the proteins examined. The proteins also showed a loss of radical scavenging capacity after treatment due to oxidation reactions. Cold plasma treatment improved protein solubility but significantly reduced emulsifying and foaming properties for all proteins. The enhancements in digestibility and bioactivity can be attributed to structural unfolding and the exposure of reactive sites on the proteins. Plant‐based food innovations like 3D printing enable the creation of customized products with unique textures and shapes, mimicking animal‐based foods while tailoring nutrition to individual needs. These technologies have the potential to revolutionize the food industry by providing sustainable and efficient ways to support plant‐based innovations such as animal protein mimetics, subtracted for 3D printing, and tailored nutritional applications in specialized diets.

Enhancing emulsification properties of pea protein isolate: Impact of heat treatment and soy hull polysaccharides on conformational modification and stability.

Enhancing emulsification properties of pea protein isolate: Impact of heat treatment and soy hull polysaccharides on conformational modification and stability.

The effect of co-precipitation and high-pressure treatment on functional and structural properties of millet and moringa protein.

The effect of co-precipitation and high-pressure treatment on functional and structural properties of millet and moringa protein.

Reversible and irreversible changes in protein secondary structure in the heat- and shear-induced texturization of native pea protein isolate

Reversible and irreversible changes in protein secondary structure in the heat- and shear-induced texturization of native pea protein isolate

Effect of protein oxidation on the quality of abalone (Haliotis discus hannai) during frozen storage under different packaging conditions.

Effect of protein oxidation on the quality of abalone (Haliotis discus hannai) during frozen storage under different packaging conditions.

Investigating the Effects of Protein Thermal Denaturation on Water-Holding Capacity of Beef: Insights from Structural Dynamics

Abstract Investigating the effects of protein thermal denaturation on beef’s water-holding capacity (WHC), the study employed differential scanning calorimetry (DSC) and Raman spectroscopy. It was found that proteins in beef denatured in a sequence starting with the myosin head, followed by the myosin tail, sarcoplasmic proteins, and lastly actin. The application of Raman spectroscopy showed that as the heating temperature increased from 40 to 100 °C, there was a shift towards more β-turns and fewer α-helices in the protein secondary structures, indicating the extent of protein denaturation and its subsequent effect on WHC. Notably, the WHC was significantly compromised between 60–80 °C due to extensive water loss from protein denaturation. However, at temperatures above 80 °C, the partial denaturation of collagen led to an enhanced WHC by creating a gel network. The findings of this study shed light on the thermal denaturation process of beef proteins and contribute to a foundational understanding for the meat processing industry to improve meat quality.

The mechanisms of thermal processing techniques on modifying structural, functional and flour-processing properties of whole-grain highland barley.

The mechanisms of thermal processing techniques on modifying structural, functional and flour-processing properties of whole-grain highland barley.

Study on structure, properties and formation mechanism of cassava starch-faba bean protein heat-induced gel.

Study on structure, properties and formation mechanism of cassava starch-faba bean protein heat-induced gel.

Polyphenol oxidase mediated (-)-epigallocatechin gallate stabilized protein in body wall of Apostichopus japonicus: Characteristics and structure.

Polyphenol oxidase mediated (-)-epigallocatechin gallate stabilized protein in body wall of Apostichopus japonicus: Characteristics and structure.

Effect of resonance acoustic mixing treatment on the gelation properties of pea protein isolate and the gel in vitro digestibility.

Effect of resonance acoustic mixing treatment on the gelation properties of pea protein isolate and the gel in vitro digestibility.

Effects of ohmic heating thawing under an appropriate electric field on the quality and structure of duck breast meat.

Ohmic heating thawing (OHT), as a novel thawing technique, possesses distinct advantages and is currently garnering attention from researchers. We have investigated the effects of OHT on the structure and protein quality of duck breast meat. Compared to conventional thawing (CT) methods (water thawing [WT], 20±0.5°C; air thawing [AT], 20±0.5°C), OHT (10, 15, and 20V/cm) has been shown to enhance thawing efficiency, reducing thawing time by 28%-86% (p<0.05), lowering thawing loss rates by 2.55% (p<0.05), and resulting in milder protein oxidation with better preservation of protein secondary structures. Microscopically, OHT resulted in minimal damage to myofibrils in the duck breast meat. In this experiment, the optimal thawing electric field strength for duck breast was 15V/cm. Moreover, the efficacy of OHT also relies on variations in voltage, with the most suitable thawing voltage determined by the specific characteristics of the material. These findings reveal the potential of OHT for thawing meat products. PRACTICAL APPLICATION: Ohmic heating thawing (OHT) shortens thawing time and enhances thawing efficiency while reducing thawing loss rates. It has a minimal impact on proteins and a minor effect on muscle fiber structure.

Exploring post-bariatric plasma metabolic changes using ATR-FTIR spectroscopy: Clinical insights and molecular perspectives.

Exploring post-bariatric plasma metabolic changes using ATR-FTIR spectroscopy: Clinical insights and molecular perspectives.

Peptide bonds revisited.

Understanding the structural and chemical properties of peptide bonds within protein secondary structures is vital for elucidating their roles in protein folding, stability and function. This study examines the distinct characteristics of peptide bonds in α-helices and β-strands using a nonredundant data set comprising 1024 high-resolution protein crystal structures from the Protein Data Bank (PDB). The analysis reveals surprising and intriguing insights into bond lengths, angles, dihedral angles, electron-density distributions and hydrogen bonding within α-helices and β-strands. While the respective bond lengths (CN and CO) do not differ much between helices and strands, the bond angles (∠CNCα and ∠OCN) are significantly larger in strands compared with helices. Furthermore, the peptide dihedral angle (ω) in helices clusters around 180° and follows a sharp Gaussian distribution with a standard deviation of 4.1°. In contrast, the distribution of dihedral angles in strands spans a much wider range, with a more flattened Gaussian peak around 180°. This distinct difference in the distribution of dihedral angles reflects the unique structural characteristics of helices and strands, highlighting their respective conformational preferences. Additionally, if the ratio of the electron-density values (2mFo - DFc) at the midpoint of the CO bond and of the CN bond is calculated, a skewed distribution is observed, with the ratio being lower for helices than for strands. Moreover, higher normalized mean atomic displacement parameters (ADPs) for peptide atoms in helices relative to strands suggest increased flexibility or a more dynamic structure within helical regions. Analysis of hydrogen-bond distances between O and N atoms of the main chain reveals larger distances in helices compared with strands, indicative of distinct hydrogen-bonding patterns associated with different secondary structures. All of these observations taken together led us to conclude that peptide bonds in α-helices are different from peptide bonds in β-strands. Overall, α-helical peptide bonds seem to display a more enol-like character. This suggests that peptide oxygen atoms in helices are more likely to be protonated. These findings have several important implications for refining protein structures, particularly in regions susceptible to enol-like transitions or protonation. By recognizing the distinct bond-angle and bond-length variations associated with protonated carbonyl oxygen atoms, current refinement protocols can be adapted to apply more flexible restraints in these regions. This could improve the accuracy of modelling local geometries, where protonation or enol forms lead to subtle structural deviations from the canonical bond parameters typically enforced in refinement strategies.

Quantification of Protein Secondary Structures from Discrete Frequency Infrared Images Using Machine Learning.

Discrete frequency infrared (IR) imaging is an exciting experimental technique that has shown promise in various applications in biomedical science. This technique often involves acquiring IR absorptive images at specific frequencies of interest that enable pathologically relevant chemical contrast. However, certain applications, such as tracking the spatial variations in protein secondary structure of tissue specimens, necessary for the characterization of neurodegenerative diseases, require deeper analysis of spectral data. In such cases, the conventional analytical approach involves band fitting the hyperspectral data to extract the relative populations of different structures through their fitted areas under the curve (AUC). While Gaussian spectral fitting for one spectrum is viable, expanding that to an image with millions of pixels, as often applicable for tissue specimens, becomes a computationally expensive process. Alternatives like principal component analysis (PCA) are less structurally interpretable and incompatible with sparsely sampled data. Furthermore, this detracts from the key advantages of discrete frequency imaging by necessitating the acquisition of more finely sampled spectral data that is optimal for curve fitting, resulting in significantly longer data acquisition times, larger datasets, and additional computational overhead. In this work, we demonstrate that a simple two-step regressive neural network model can be utilized to mitigate these challenges and employ discrete frequency imaging for retrieving the results from band fitting without significant loss of fidelity. Our model reduces the data acquisition time nearly six-fold by requiring only seven wavenumbers to accurately interpolate spectral information at a higher resolution and subsequently using the upscaled spectra to accurately predict the component AUCs, which is more than 3000 times faster than spectral fitting. Our approach thus drastically cuts down the data acquisition and analysis time and predicts key differences in protein structure that can be vital towards broadening potential applications of discrete frequency imaging.