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Foods (Basel, Switzerland) Jul 2023The kinetic properties and thermal characteristics of fresh pork meat proteins (), as well as osmotically dehydrated meat proteins, were investigated using differential...
The kinetic properties and thermal characteristics of fresh pork meat proteins (), as well as osmotically dehydrated meat proteins, were investigated using differential scanning calorimetry. Two isoconversional kinetical methods, namely the differential Friedman and integral Ortega methods, were employed to analyze the data. The obtained kinetic triplet, activation energy, pre-exponential factor, and extent of conversion, has been discussed. The resulting activation energy for proteins of fresh meat ranges between 751 kJ·mol for myosin, 152 kJ·mol for collagen and sarcoplasmic proteins, and 331 kJ·mol for actin at a conversion degree of 0.1 to 0.9. For osmotically dried pork meat proteins, the values range from 307 kJ·mol for myosin 272 kJ·mol for collagen and sarcoplasmic proteins, and 334.83 kJ·mol for actin at a conversion degree from 0.1 to 0.9. The proteins of the dry meat obtained by osmotic dehydration in molasses could be described as partly unfolded as they retain the characteristic protein denaturation transition. Concerning the decrease in enthalpies of proteins denaturation, thermodynamic destabilization of dried meat proteins occurred. On the contrary, dried meat proteins were thermally stabilized with respect to increase in the temperatures of denaturation. Knowledge of the nature of meat protein denaturation of each kind of meat product is one of the necessary tools for developing the technology of meat product processing and to achieve desired quality and nutritional value. The kinetic analysis of meat protein denaturation is appropriate because protein denaturation gives rise to changes in meat texture during processing and directly affects the quality of product.
PubMed: 37569136
DOI: 10.3390/foods12152867 -
Food Chemistry: X Dec 2022Physicochemical, proteomics, and bioinformatics analyses were conducted to investigate protein profiles in under frozen (120 d) and chilled (6 d) storage. Springiness,...
Physicochemical, proteomics, and bioinformatics analyses were conducted to investigate protein profiles in under frozen (120 d) and chilled (6 d) storage. Springiness, chewiness, myofibrillar active sulfhydryl content, and Ca-ATPase activity significantly decreased, suggesting that cold stress altered muscle proteins. Compared with fresh hairtail (FH), 66 common differentially abundant proteins (DAPs) had lower abundances in chilled (3 d; CSH) and frozen (120 d; FSH) hairtail, including myosin binding proteins, filamins, actinin, troponin, and muscle-restricted coiled-coil protein. Gene Ontology (GO) annotation showed DAPs were mainly involved in cellular process, cellular anatomical entity, intracellular, and binding items. Eukaryotic orthologous group (KOG) analysis revealed that changes in cytoskeleton and energy production and conversion functions dominated during cold storage, degrading the myofibril and connective tissue structures and the physicochemical performance of muscle tissues. This study presents deep insights into the protein alternation mechanisms in hairtail muscle under cold stress.
PubMed: 36277867
DOI: 10.1016/j.fochx.2022.100479 -
Food Research International (Ottawa,... Nov 2022A plethora of different factors, such as heat treatment, pH, soluble calcium and phosphate concentrations, colloidal calcium phosphate, ionic strength, redox potential,...
A plethora of different factors, such as heat treatment, pH, soluble calcium and phosphate concentrations, colloidal calcium phosphate, ionic strength, redox potential, etc., affect functionally of critical milk components such as casein micelles, fat globules and whey proteins. These physicochemical changes induce fat- or protein-protein interactions that would be associated to changes in particle size that might be revealed using light backscatter measurements. We hypothesized that inline, simple, low-cost light backscatter measurements might have the potential to provide functionally related information, representing an interesting opportunity for process control. Casein micelle particle size and near infrared light backscatter spectra were measured in milks heat treated at 80 and 90 °C and pH 6.3, 6.7 and 7.1 in order to obtain prediction models for estimating changes in casein micelle particle size during milk heat treatment. Light intensity was measured over a spectral range of 200-1100 nm using a simple optical backscatter sensor and was implemented into models for particle size predictions as a function of heat treatment temperature and pH. Models which included an exponential factor containing a ratio of two specific wavebands were found to improve R when compared to single wavelength models. The best model exhibited an R of 0.993 and SEP of 2.36 nm. The developed prediction models show promise for in-line monitoring of whey protein denaturation and casein micelle particle size.
Topics: Animals; Calcium; Caseins; Hot Temperature; Hydrogen-Ion Concentration; Micelles; Milk; Particle Size; Phosphates; Whey Proteins
PubMed: 36192923
DOI: 10.1016/j.foodres.2022.111745 -
Heliyon Nov 2022Even though nanotechnology is extensively applied in agriculture, biochemistry, medicine and many other sectors, it is a developing field that conforms to new and more... (Review)
Review
Even though nanotechnology is extensively applied in agriculture, biochemistry, medicine and many other sectors, it is a developing field that conforms to new and more complex applications in food systems as compared to other technologies. It offers a viable strategy for integrating cutting-edge technology into a wide range of operations related to the production, development, fabrication, packaging, storage and distribution of food. The most fundamentally sophisticated technology in nano-based food science, nanoparticles deal with a wide range of nanostructured materials and nano methods, including nanofood, nanotubes, nanocomposites, nano packaging, nanocapsules, nanosensors, liposomes, nanoemulsions, polymeric nanoparticles and nanoencapsulation. This method is developed to increase food solubility and shelf life, availability of bioactive chemical, the protection of food constituents, nutritional supplementation, fortification and food or constituent delivery. Additionally, it serves as an antibacterial agent by generating reactive oxygen species (ROS) which cause bacterial DNA damage, protein denaturation and cell damage. Although the use of nanotechnology in food applications is advancing, there are certain negative or dangerous effects on health related to the toxicity and dangers of ingesting nanoparticles in food. The use of nanotechnology in the food industry, notably in processing, preservation and packaging, with its promising future, was addressed in this study. The toxicity of nanoparticles in food as well as its development in food safety assessments with certain areas of concern were also reviewed.
PubMed: 36444247
DOI: 10.1016/j.heliyon.2022.e11795 -
Biomolecules Mar 2020From experimental studies of protein folding, it is now clear that there are two types of folding behavior, i.e., two-state folding and non-two-state folding, and... (Review)
Review
From experimental studies of protein folding, it is now clear that there are two types of folding behavior, i.e., two-state folding and non-two-state folding, and understanding the relationships between these apparently different folding behaviors is essential for fully elucidating the molecular mechanisms of protein folding. This article describes how the presence of the two types of folding behavior has been confirmed experimentally, and discusses the relationships between the two-state and the non-two-state folding reactions, on the basis of available data on the correlations of the folding rate constant with various structure-based properties, which are determined primarily by the backbone topology of proteins. Finally, a two-stage hierarchical model is proposed as a general mechanism of protein folding. In this model, protein folding occurs in a hierarchical manner, reflecting the hierarchy of the native three-dimensional structure, as embodied in the case of non-two-state folding with an accumulation of the molten globule state as a folding intermediate. The two-state folding is thus merely a simplified version of the hierarchical folding caused either by an alteration in the rate-limiting step of folding or by destabilization of the intermediate.
Topics: Circular Dichroism; Kinetics; Protein Conformation; Protein Denaturation; Protein Folding; Proteins
PubMed: 32155758
DOI: 10.3390/biom10030407 -
Proceedings of the National Academy of... Apr 2024Trimethylamine-N-oxide (TMAO) and urea are metabolites that are used by some marine animals to maintain their cell volume in a saline environment. Urea is a well-known...
Trimethylamine-N-oxide (TMAO) and urea are metabolites that are used by some marine animals to maintain their cell volume in a saline environment. Urea is a well-known denaturant, and TMAO is a protective osmolyte that counteracts urea-induced protein denaturation. TMAO also has a general protein-protective effect, for example, it counters pressure-induced protein denaturation in deep-sea fish. These opposing effects on protein stability have been linked to the spatial relationship of TMAO, urea, and protein molecules. It is generally accepted that urea-induced denaturation proceeds through the accumulation of urea at the protein surface and their subsequent interaction. In contrast, it has been suggested that TMAO's protein-stabilizing effects stem from its exclusion from the protein surface, and its ability to deplete urea from protein surfaces; however, these spatial relationships are uncertain. We used neutron diffraction, coupled with structural refinement modeling, to study the spatial associations of TMAO and urea with the tripeptide derivative glycine-proline-glycinamide in aqueous urea, aqueous TMAO, and aqueous urea-TMAO (in the mole ratio 1:2 TMAO:urea). We found that TMAO depleted urea from the peptide's surface and that while TMAO was not excluded from the tripeptide's surface, strong atomic interactions between the peptide and TMAO were limited to hydrogen bond donating peptide groups. We found that the repartition of urea, by TMAO, was associated with preferential TMAO-urea bonding and enhanced urea-water hydrogen bonding, thereby anchoring urea in the bulk solution and depleting urea from the peptide surface.
Topics: Animals; Urea; Peptides; Water; Methylamines; Membrane Proteins
PubMed: 38536756
DOI: 10.1073/pnas.2317825121 -
Frontiers in Nutrition 2022Marination is a common technology in meat processing with advantages of enhancing tenderness, water retention, and overall quality. This study was conducted to...
Marination is a common technology in meat processing with advantages of enhancing tenderness, water retention, and overall quality. This study was conducted to investigate the effect of vacuum tumbling and immersion marination on meat quality, microstructure, water mobility, protein changes, and denaturation of Xueshan chicken. Results showed that vacuum tumbling significantly increased the marinating rate of chicken, tenderness, meat texture, and water retention. Meanwhile, vacuum tumbling decreased total sulfhydryl content alongside an increased protein surface hydrophobicity and free sulfhydryl content, indicating that vacuum tumbling elevated the degree of protein denaturation. Further, the peak area corresponding to the relaxation time T after vacuum tumbling was significantly higher than that of immersion marination, suggesting that the stability of the immobilized water of chicken was reduced by vacuum tumbling. Compared to immersion marination, vacuum tumbling improved myofibril fragmentation index (MFI) presenting fewer myofibrillar protein bands in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel and more damaged muscular cells. Overall, vacuum tumbling could improve the marination absorptivity, protein degradation, and denaturation, resulting in changes in myofibril structure and meat quality of Xueshan chicken.
PubMed: 36505261
DOI: 10.3389/fnut.2022.1064521 -
Foods (Basel, Switzerland) Nov 2022This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT),...
BACKGROUND
This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT), semimembranosus (SM) and semitendinosus (ST) muscles were cut and boiled for 30 min in boiling water, followed by detection of water holding capacity (WHC), tenderness, fiber volume shrinkage and protein denaturation.
RESULTS
Compared with LT and SM, ST had the best WHC and lowest WBSF and area shrinkage ratio. The mobility of immobilized water (T22) was key to holding the water of meat. ST contained the highest content of total and heat-soluble collagen. On the contrary, ST showed the lowest content of cross-links and decorin, which indicate the IMCT strength of ST is weaker than the other two. The heat-soluble collagen is positively correlated to T22.
CONCLUSIONS
The shrinkage of heat-insoluble IMCT on WHC and WBSF may partly depend on the structural strength changes of IMCT components rather than solely caused by quantitative changes of IMCT.
PubMed: 36496643
DOI: 10.3390/foods11233835 -
Scientific Reports Nov 2020Protein folding is governed by non-covalent interactions under the benefits and constraints of the covalent linkage of the backbone chain. In the current work we...
Protein folding is governed by non-covalent interactions under the benefits and constraints of the covalent linkage of the backbone chain. In the current work we investigate the influence of loop length variation on the free energies of folding and ligand binding in a small globular single-domain protein containing two EF-hand subdomains-calbindin D. We introduce a linker extension between the subdomains and vary its length between 1 to 16 glycine residues. We find a close to linear relationship between the linker length and the free energy of folding of the Ca-free protein. In contrast, the linker length has only a marginal effect on the Ca affinity and cooperativity. The variant with a single-glycine extension displays slightly increased Ca affinity, suggesting that the slightly extended linker allows optimized packing of the Ca-bound state. For the extreme case of disconnected subdomains, Ca binding becomes coupled to folding and assembly. Still, a high affinity between the EF-hands causes the non-covalent pair to retain a relatively high apparent Ca affinity. Our results imply that loop length variation could be an evolutionary option for modulating properties such as protein stability and turnover without compromising the energetics of the specific function of the protein.
Topics: Animals; Calbindins; Calcium; Calorimetry, Differential Scanning; Cats; EF Hand Motifs; Ligands; Protein Conformation; Protein Denaturation; Protein Folding; Protein Stability; Thermodynamics
PubMed: 33208843
DOI: 10.1038/s41598-020-76598-x -
Biophysical Journal Apr 2022Yfh1 is a yeast protein with the peculiar characteristic to undergo, in the absence of salt, cold denaturation at temperatures above the water freezing point. This...
Yfh1 is a yeast protein with the peculiar characteristic to undergo, in the absence of salt, cold denaturation at temperatures above the water freezing point. This feature makes the protein particularly interesting for studies aiming at understanding the rules that determine protein fold stability. Here, we present the phase diagram of Yfh1 unfolding as a function of pressure (0.1-500 MPa) and temperature 278-313 K (5-40°C) both in the absence and in the presence of stabilizers using Trp fluorescence as a monitor. The protein showed a remarkable sensitivity to pressure: at 293 K, pressures around 10 MPa are sufficient to cause 50% of unfolding. Higher pressures were required for the unfolding of the protein in the presence of stabilizers. The phase diagram on the pressure-temperature plane together with a critical comparison between our results and those found in the literature allowed us to draw conclusions on the mechanism of the unfolding process under different environmental conditions.
Topics: Cold Temperature; Hot Temperature; Iron-Binding Proteins; Protein Denaturation; Protein Folding; Saccharomyces cerevisiae; Thermodynamics; Frataxin
PubMed: 35278425
DOI: 10.1016/j.bpj.2022.03.010