Endogenous Fluorescence Research Articles

Use of autofluorescent stomatoscopy in the diagnostic algorithm for oral mucosal and vermilion border lesions in adolescents

Relevance. There is currently significant interest in studying the prevalence of diseases affecting the oral mucosa and lip vermilion border in adolescents. A promising approach in this field is the use of modern non-invasive optical technologies, which not only offer additional insights into the patient's oral health status but also enhance their compliance.Materials and methods. A total of 71 adolescents (9th to 11th grade students) aged 15 to 17 years (mean age — 16.2 ± 0.8 years) were examined. The oral mucosa and lip vermilion border were assessed for abnormalities under natural light and through endogenous fluorescence using autofluorescent stomatoscopy. Various optical filters were applied, and clinical images were compared with autofluorescent images. A visual analog scale was used to assess the clarity of the diagnostic test results for the participant. Recommendations were provided, and treatment was prescribed according to the established diagnoses.Results. Oral mucosal lesions and lesions of the lip vermilion border were observed in 45% of cases, all of benign origin, without visible changes to the naked eye or pain. The most frequently diagnosed lesions were morsicatio buccarum and chapped lips. Distinct autofluorescent characteristics of the identified lesions were observed and documented. Participant-reported feedback was positive in 100% of cases during autofluorescent stomatoscopy. The mean score for the clarity of diagnostic results, assessed using the visual analog scale, was 9.3±0.12, indicating a high level of diagnostic visibility.Conclusion. Implementing a qualified clinical approach focused on preventing oral diseases in adolescent patients is recommended with the use of autofluorescent stomatoscopy. This technique not only offers real-time insights into the patient’s oral health status but also actively engages young patients, increasing their motivation to maintain good oral health.

In Vitro Inhibitory Mechanism of Polyphenol Extracts from Multi-Frequency Power Ultrasound-Pretreated Rose Flower Against α-Glucosidase.

This paper explored the in vitro inhibitory mechanism of polyphenol-rich rose extracts (REs) from an edible rose flower against α-glucosidase using multispectral and molecular docking techniques. Results showed that REs had an inhibitory effect on α-Glu activity (IC50 of 1.96 μg/mL); specifically, the samples pretreated by tri-frequency ultrasound (20/40/60 kHz) exhibited a significantly (p < 0.05) stronger inhibitory effect on α-Glu activity with an IC50 of 1.33 μg/mL. The Lineweaver-Burk assay indicated that REs were mixed-type inhibitors and could statically quench the endogenous fluorescence of α-Glu. REs increased the chance of polypeptide chain misfolding by altering the microenvironment around tryptophan and tyrosine residues and disrupting the natural conformation of the enzyme. Molecular docking results showed that polyhydroxy phenolics had a high fit to the active site of α-Glu, so REs with high polymerization and numerous phenolic hydroxyl groups had a stronger inhibitory effect. Therefore, this study provides new insights into polyphenol-rich REs as potential α-glucosidase inhibitors.

Insights into the enhanced adsorption of glyphosate by dissolved organic matter in farmland Mollisol: effects and mechanisms of action.

Dissolved organic matter (DOM) is easy to combine with residual pesticides and affect their morphology and environmental behavior. Given that the binding mechanism between DOM and the typical herbicide glyphosate in soil is not yet clear, this study used adsorption experiments, multispectral techniques, density functional theory, and pot experiments to reveal the interaction mechanism between DOM and glyphosate on Mollisol in farmland and their impact on the environment. The results show that the adsorption of glyphosate by Mollisol is a multilayer heterogeneous chemical adsorption process. After adding DOM, due to the early formation of DOM and glyphosate complex, the adsorption process gradually became dominated by single-layer chemical adsorption, and the adsorption capacity increased by 1.06 times. Glyphosate can quench the endogenous fluorescence of humic substances through a static quenching process dominated by hydrogen bonds and van der Waals forces, and instead enhance the fluorescence intensity of protein substances by affecting the molecular environment of protein molecules. The binding of glyphosate to protein is earlier, of which affinity stronger than that of humic acid. In this process, two main functional groups (C-O in aromatic groups and C-O in alcohols, ethers and esters) exist at the binding sites of glyphosate and DOM. Moreover, the complexation of DOM and glyphosate can effectively alleviate the negative impact of glyphosate on the soil. This study has certain theoretical guidance significance for understanding the environmental behavior of glyphosate and improving the sustainable utilization of Mollisol.

Structural and in vitro anticancer properties of the kaempferol–lactoferrin complex

AbstractLactoferrin and polyphenols are common natural functional compounds. Their interactions and the consequential alterations in functional activity have received widespread attention. The work aimed to investigate the interaction between lactoferrin and kaempferol, as well as evaluate the in vitro anticancer properties of the lactoferrin–kaempferol complex. The results of the spectra experiments revealed that lactoferrin and kaempferol are capable of forming complexes to quench the endogenous fluorescence of lactoferrin. Further insight into the binding mechanism was gained through molecular docking and molecular dynamics simulations. These analyses suggest that both hydrophobic interactions and hydrogen bonding are essential factors in the interaction between lactoferrin and kaempferol. Furthermore, the MTT assay and apoptosis by flow cytometry were conducted, revealing a synergistic effect of kaempferol and lactoferrin on the inhibition of HeLa cell proliferation. The findings from this investigation could improve our understanding of lactoferrin's interaction with polyphenols and the role of the lactoferrin–kaempferol complex in inhibiting cancer cell proliferation.

Effects of Soy Protein Isolate and Inulin Conjugate on Gel Properties and Molecular Conformation of Spanish Mackerel Myofibrillar Protein.

The gel properties and molecular conformation of Spanish mackerel myofibrillar protein (MP) induced by soy protein isolate-inulin conjugates (SPI-inulin conjugates) were investigated. The addition of SPI-inulin conjugates significantly enhanced the quality of the protein gel. An analysis of different additives was conducted to assess their impact on the gel strength, texture, water-holding capacity (WHC), water distribution, intermolecular force, dynamic rheology, Raman spectrum, fluorescence spectrum, and microstructure of MP. The results demonstrated a substantial improvement in the strength and water retention of the MP gel with the addition of the conjugate. Compared with the control group (MP), the gel strength increased from 35.18 g·cm to 41.90 g·cm, and WHC increased from 36.80% to 52.67% with the inclusion of SPI-inulin conjugates. The hydrogen bond content was notably higher than that of other groups, and hydrophobic interaction increased from 29.30% to 36.85% with the addition of SPI-inulin conjugates. Furthermore, the addition of the conjugate altered the secondary structure of the myofibrillar gel, with a decrease in α-helix content from 62.91% to 48.42% and an increase in β-sheet content from 13.40% to 24.65%. Additionally, the SPI-inulin conjugates led to a significant reduction in the endogenous fluorescence intensity of MP. Atomic force microscopy (AFM) results revealed a substantial increase in the Rq value from 8.21 nm to 20.21 nm. Adding SPI and inulin in the form of conjugates is an effective method to improve the gel properties of proteins, which provides important guidance for the study of adding conjugates to surimi products. It has potential application prospects in commercial surimi products.

Investigation on the anti-α-glucosidase mechanism of aspergillus triazolate A from Oxalis corniculate L.

Diabetes mellitus characterized by abnormal glucose concentration is a metabolic disease. α-Glu inhibitors from natural sources are a good choice for searching for high-efficiency and low-toxicity hypoglycemic drugs. In this study, a naturally effective α-Glu inhibitor aspergillus triazolate A (ATA) with a peculiar structure was first found in Oxalis corniculate L., then its activity and mechanism were first elucidated through various methods. These mechanisms included enzyme kinetics, circular dichroism spectra, fluorescence spectra, synchronous fluorescence spectrum, 3D fluorescence spectrum, and molecular docking. Meanwhile, the ability to reduce postprandial blood glucose was further investigated in vivo. Research results revealed that ATA was a mixed type α-Glu inhibitor with an IC50 value of 66.87 ± 1.50 μM, which bound to the enzyme from a single site through hydrogen bonding and hydrophobic forces causing the looser secondary structure of α-Glu. It was also found that the binding site of α-Glu was closer to the Trp residue, and the endogenous fluorescence of α-Glu was quenched in a static quenching form. Moreover, the sucrose loading test in vivo revealed that the ATA of 20 mg/kg could effectively reduce the postprandial blood glucose level. Hence, ATA could be used as lead compound to develop novel α-Glu inhibitors.

The study on characterization of interaction between casticin and model proteins using spectroscopic and computational methodologies

The present studies were conducted to investigate the interaction of casticin to model proteins (BSA, HSA, OVA and HEL) using fluorescence spectra, Fourier transform infrared spectra, molecular docking and molecular dynamics simulation methodologies. Our work displayed that the endogenous fluorescence intensities of BSA, HSA, OVA and HEL were quenched by various concentrations of casticin were the typical static quenching process. The binding constants (Ka) of casticin for these model proteins were in the range of 104–105 mol·L-1, with the highest affinity for HSA. On the basis of thermodynamic parameters and computational simulation studies, it was suggested that the binding force of casticin to BSA, HSA, OVA and HEL were mainly hydrogen bonds, van der Waals forces and hydrophobic interactions. The spectral results illustrated that the binding of casticin to BSA, HSA, OVA and HEL induced conformational and microenvironmental changes. Casticin could decrease the α-helix percentages of BSA, HSA and OVA, but increase that of HEL. Binding substitution studies confirmed that casticin bound to the Sudlow site I of BSA and HSA. Molecular docking predicted the binding models of casticin to BSA, HSA, OVA and HEL, followed closely by molecular dynamic simulations to assess the binding stability.

FLUID: a fluorescence-friendly lipid-compatible ultrafast clearing method.

Many clearing methods achieve high transparency by removing lipid components from tissues, which damages microstructure and limits their application in lipid research. As for methods which preserve lipid, it is difficult to balance transparency, fluorescence preservation and clearing speed. In this study, we propose a rapid water-based clearing method that is fluorescence-friendly and preserves lipid components. FLUID allows for preservation of endogenous fluorescence over 60 days. It shows negligible tissue distortion and is compatible with various types of fluorescent labeling and tissue staining methods. High quality imaging of human brain tissue and compatibility with pathological staining demonstrated the potential of our method for three-dimensional (3D) biopsy and clinical pathological diagnosis.

Multi-modal, Label-free, Optical Mapping of Cellular Metabolic Function and Oxidative Stress in 3D Engineered Brain Tissue Models.

Brain metabolism is essential for the function of organisms. While established imaging methods provide valuable insights into brain metabolic function, they lack the resolution to capture important metabolic interactions and heterogeneity at the cellular level. Label-free, two-photon excited fluorescence imaging addresses this issue by enabling dynamic metabolic assessments at the single-cell level without manipulations. In this study, we demonstrate the impact of spectral imaging on the development of rigorous intensity and lifetime label-free imaging protocols to assess dynamically over time metabolic function in 3D engineered brain tissue models comprising human induced neural stem cells, astrocytes, and microglia. Specifically, we rely on multi-wavelength spectral imaging to identify the excitation/emission profiles of key cellular fluorophores within human brain cells, including NAD(P)H, LipDH, FAD, and lipofuscin. These enable development of methods to mitigate lipofuscin's overlap with NAD(P)H and flavin autofluorescence to extract reliable optical metabolic function metrics from images acquired at two excitation wavelengths over two emission bands. We present fluorescence intensity and lifetime metrics reporting on redox state, mitochondrial fragmentation, and NAD(P)H binding status in neuronal monoculture and triculture systems, to highlight the functional impact of metabolic interactions between different cell types. Our findings reveal significant metabolic differences between neurons and glial cells, shedding light on metabolic pathway utilization, including the glutathione pathway, OXPHOS, glycolysis, and fatty acid oxidation. Collectively, our studies establish a label-free, non-destructive approach to assess the metabolic function and interactions among different brain cell types relying on endogenous fluorescence and illustrate the complementary nature of information that is gained by combining intensity and lifetime-based images. Such methods can improve understanding of physiological brain function and dysfunction that occurs at the onset of cancers, traumatic injuries and neurodegenerative diseases.

Investigation of the interaction mechanism and enzyme activity of trypsin with cerium oxide nanoparticles

In this study, the interaction mechanism and native conformational variation of trypsin (Try) affected by CeO2 nanoparticles (NPs) were systematically studied via various spectroscopic methods. The results of fluorescence spectroscopy revealed that CeO2 NPs markedly quenched the endogenous fluorescence of Try via the mechanism of static quenching. The main forces that contributed to the binding of Try and CeO2 NPs were van der Waals forces, hydrogen bonds, and electrostatic forces, as observed by the binding constants and significant thermodynamic characteristics of the two substances. The incorporation of CeO2 NPs lead to a slight change in the structure of Try, as shown by synchronized fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and circular dichroism (CD) spectroscopy. Moreover, the enzyme activity of Try decreased with the addition of CeO2 NPs. This study is highly important for fully evaluating the use of CeO2 NPs in biomedical sciences and is helpful for clarifying the mechanism between Try and CeO2 NPs at the molecular level.

Formation mechanism of giant squid myofibrillar protein aggregates induced by egg white protein during heat treatment

In order to solve the problem of poor performance of giant squid gel, this study proposed a method to induce the aggregation of giant squid protein molecules by exogenous additives to improve its gel performance. The particle size, zeta potential, free sulfhydryl group, carbonyl group and hydrophobic index of protein solution were characterized by laser light scattering, fluorescence spectrum and ultraviolet spectrum, and the effect of egg white protein (EWP) on myofibrillar protein (MP) aggregation was analyzed. In the presence of EWP, the density and Rg/Rh value of protein particles decreased significantly after mixing for 600 min, indicating that the interaction between MP and EWP protein could be enhanced by embedding appropriate amount of EWP in the middle of MP protein. With the increase of the proportion of egg white protein, the blue shift of the maximum absorption wavelength of endogenous fluorescence in the mixed protein solution decreased. In the range of 25–65 °C, the change rates of surface charge, free sulfhydryl group, carbonyl group and surface hydrophobicity decreased, which proved that EWP inhibited the self-aggregation rate of MP molecules during the heating process, and induced its gel by interspersing between MP molecules to improve the formation of three-dimensional network during protein thermal gel process. Finally, the addition of EWP improved the gel properties of giant squid surimi. This study offered new direction for improving gel properties and promotes the development and application of giant squid.

Breaking Biomphalaria black box by in situ revelation of fluorescent Schistosoma mansoni parasites

Tissue clearing is an old-fashioned method developed in the 1900's and used to turn an opaque biological object into a 3D visualizable transparent structure. Developed and diversified over the last decade, this method is most of the time applied to mammals' tissues, and especially mouse and human tissues for cytological, histological and pathophysiological studies. Through autofluorescence, immunofluorescence, in situ hybridization, intercalating agents, fluorescent transfection markers or fluorescent particle uptake, optically cleared samples can be monitored to discover new biological structures and cellular interactions through 3D-visualization, which can be more challenging in some extend through classical histological methods. Most of the tissue clearing procedures have been developed for specific applications like endogenous fluorescence visualization, immunolabeling or for revealing specific organs. Thus, choosing the adapted protocol may be empirical for non-model species, especially for mollusks for which very little related literature is available. Herein, we suggest an effective optical tissue clearing procedure for the freshwater snail Biomphalaria glabrata, known as the intermediate host of the human parasite Schistosoma mansoni. This clearing procedure involves solvents with a minimal toxicity, preserves the endogenous fluorescence of labeled parasites inside snail tissues and is compatible with an immunolabeling procedure.

Exploring intermolecular interaction between transporter protein, bovine serum albumin and antitumor drug Lorlatinib: Multispectral approaches combined with molecular simulation

In this paper, the intermolecular interaction of antitumor drug loratinib (LOR) with the transporter protein, bovine serum albumin (BSA) was researched utilizing multiple spectroscopic approaches combined with molecular modeling. The experimental outcomes showed that LOR entered the hydrophobic gap between the two subintervals of BSA (site II '), formed the ground-state complex with a stoichiometric ratio of 1:1, and statically quenched the endogenous fluorescence of BSA protein. During the intermolecular interaction between the two, the binding constant was with the interval of 104-106 M−1, indicating a moderate to strong affinity between the two. In addition, there was a non-radiative energy transfer from BSA to LOR, and binding with LOR diminished the α-helix content of BSA protein and affected slightly on the microenvironment surrounding the aromatic amino acids like Trp and Tyr residues. The binding of LOR to BSA was inhibited by most common metal ions, and only the Fe3+ ion promoted it. The outcomes of experiments as well as molecular dynamics simulation showed that the primary binding forces between LOR and BSA were hydrogen bonding, hydrophobic force and van der Waals force.

Inactivation of Cronobacter sakazaki by phloretin: Molecular insights into targeting SdiA and practical applications

The quorum sensing receptor SdiA is vital for the environmental resistance of Cronobacter sakazakii, facilitating its survival in powdered infant formula (PIF). In this study, a three-dimensional model of the SdiA receptor was developed, and molecular docking was used to screen inhibitors targeting SdiA. The interaction mechanisms and the blocking effect of inhibitors on quorum sensing were also validated. Among hit compounds, phloretin significantly reduced the environmental resistance of the wild type (WT) at a sub-inhibitory concentration of 0.6 mg/mL (p < 0.05), lowering the survival rates from 4.61, 5.65, and 5.32 log to 2.76, 1.30, and 1.71 log under heat, osmotic, and desiccation stress, respectively. In simulated aqueous conditions, the stability of phloretin-SdiA complex was maintained throughout over 70 ns, with van der Waals forces and electrostatic interactions crucial for its structural stability. The interactions between phloretin and SdiA lead to a discernible increase in the UV absorption and a significant quenching of the endogenous fluorescence of the SdiA protein, with the α-helical content increasing from 54.3% to 65.2%. Additionally, inoculation of 4 log10 CFU/mL of WT in dry powder materials of PIF, combined with phloretin at a concentration of 0.6 mg/mL and simulation of evaporation and drying processes, reduced WT below detection limit for enumeration. The outcomes of this study provide valuable scientific evidence and insights for developing innovative prevention and control strategies against C. sakazakii.

Annual variation in thermal and structural properties of yesso scallops (Mizuhopecten yessoensis) adductor muscle

The annual changes of the scallop’s adductor muscle in Ca2+-ATPase activity, chymotryptic digestion, endogenous fluorescence spectra, sulfhydryl content, and surface hydrophobicity were studied. Ca2+-ATPase activity peaked in February and reached its minimum in August for males and in July for females. However, no significant differences were observed between males and females throughout the year. The inactivation rate of Ca2+-ATPase activity increased by 17- to 36-fold when the temperature rose from 38°C to 45°C. The ratio of free myosin to bound myosin was approximately 5:4 at 0.5 M KCl and changed to 5:1 at 1.0 M, as determined by modeling. Chymotryptic digestion demonstrated that scallop myosin could be cleaved into S-1/rod portions at 0.1 M and HMM/LMM at 0.5 M KCl. Furthermore, no significant seasonal variations were observed in chymotryptic digestion patterns, endogenous fluorescence, surface hydrophobicity, or sulfhydryl content. In conclusion, the structure and thermal stability of both male and female scallops remained stable throughout the year, making them suitable for processing and preservation.

Metabolic profiling of single cells by exploiting NADH and FAD fluorescence via flow cytometry

ObjectiveThe metabolism of different cells within the same microenvironment can differ and dictate physiological or pathological adaptions. Current single-cell analysis methods of metabolism are not label-free. MethodsThe study introduces a label-free, live-cell analysis method assessing endogenous fluorescence of NAD(P)H and FAD in surface-stained cells by flow cytometry. ResultsOxPhos inhibition, mitochondrial uncoupling, glucose exposure, genetic inactivation of glucose uptake and mitochondrial respiration alter the optical redox ratios of FAD and NAD(P)H as measured by flow cytometry. Those alterations correlate strongly with measurements obtained by extracellular flux analysis. Consequently, metabolically distinct live B-cell populations can be resolved, showing that human memory B-cells from peripheral blood exhibit a higher glycolytic flexibility than naïve B cells. Moreover, the comparison of blood-derived B- and T-lymphocytes from healthy donors and rheumatoid arthritis patients unleashes rheumatoid arthritis-associated metabolic traits in human naïve and memory B-lymphocytes. ConclusionsTaken together, these data show that the optical redox ratio can depict metabolic differences in distinct cell populations by flow cytometry.

Mechanism understanding of PIKfyve inhibitor YM201636 with human serum albumin: Insights from molecular modeling and multiple spectroscopic techniques.

YM201636 is the potent PIKfyve inhibitor that is being actively investigated for liver cancer efficacy. In this study, computer simulations and experiments were conducted to investigate the interaction mechanism between YM201636 and the transport protein HSA. Results indicated that YM201636 is stably bound between the subdomains IIA and IIIA of HSA, supported by site marker displacement experiments. YM201636 quenched the endogenous fluorescence of HSA by static quenching since a decrease in quenching constants was observed from 7.74 to 2.39 × 104 M-1. UV-vis and time-resolved fluorescence spectroscopy confirmed the YM201636-HSA complex formation and this binding followed a static mechanism. Thermodynamic parameters ΔG, ΔH, and ΔS obtained negative values suggesting the binding was a spontaneous process driven by Van der Waals interactions and hydrogen binding. Binding constants ranged between 5.71 and 0.33 × 104 M-1, which demonstrated a moderately strong affinity of YM201636 to HSA. CD, synchronous, and 3D fluorescence spectroscopy revealed that YM201636 showed a slight change in secondary structure. The increase of Kapp and a decrease of PSH with YM201636 addition showed that YM201636 changed the surface hydrophobicity of HSA. The research provides reasonable models helping us further understand the transportation and distribution of YM201636 when it absorbs into the blood circulatory system.

Synthesis and Characterization of Emulsifiers Based on the Maillard Reaction and Its Application in Stabilized DHA Algal Oil Nanoemulsions.

The aim of this study was to optimize the formation of sodium caseinate (CS) and gum arabic (GA) complexes through the Maillard reaction and to evaluate their effectiveness in improving the emulsification properties and stability of docosahexaenoic acid (DHA) nanoemulsions. First, the best target polysaccharides were selected, and the best modification conditions were determined using orthogonal experiments. Secondly, the response surface experiments were used to optimize the preparation process of the emulsion. The stability, in vitro digestion characteristics, and rheological characteristics of the emulsion prepared by means of CS-GA were compared with the emulsion prepared using a whey protein isolate (WPI). After the orthogonal test, the optimal modification conditions were determined to be a reaction time of 96 h, a CS-GA mass ratio of 1:2, a reaction temperature of 60 °C, and a degree of grafting of 44.91%. Changes in the infrared (IR), Raman, ultraviolet (UV), and endogenous fluorescence spectra also indicated that the complex structure was modified. The response surface test identified the optimal preparation process as follows: an emulsifier concentration of 5 g/L, an oil-phase concentration of 5 g/L, and a homogenization frequency of five, and the emulsion showed good stability. Therefore, the use of a nanoemulsion as a nanoscale DHA algal oil delivery system is very promising for extending the shelf life and improving the stability of food.

Investigating the impact of common migration substances found in milk packaging on proteases: A multispectral and molecular docking approach

The effects of common migration substances in milk packaging on digestive protease were studied. We choose the common migrants found in eight types of multi-layer composite milk packaging. Enzyme activity experiments revealed that pepsin activity decreased by approximately 18 % at 500 μg/mL of stearic acid and stearamide treatment, while trypsin activity decreased by approximately 18 % only by stearic acid treatment (500 μg/mL). Subsequently, fluorescence spectroscopy, circular dichroism spectroscopy, and molecular docking technology were employed to investigate the inhibition mechanism of protease activity by migrating substances in three systems: stearic acid-trypsin, stearic acid-pepsin, and stearamide-pepsin. Results showed that the inhibitory effect of stearic acid on trypsin is a reversible mixed inhibition, whereas the inhibitory effects of stearic acid and stearamide on pepsin are non-competitive. In all three systems, ΔH < 0, ΔS < 0, and ΔG < 0, indicating the binding process between the migrant and the protease is a spontaneous exothermic process primarily driven by hydrogen bonding and van der Waals forces. In addition, their binding constants are all around 104 L/moL, indicating that there are moderate binding affinities exist between migrants and proteases. The binding process results in the quenching of the protease's endogenous fluorescence and induces alterations in the enzyme's secondary structure. Synchronized fluorescence spectroscopy showed that stearic acid enhanced the hydrophobicity near the Tyr residue of trypsin. The molecular docking results indicated that the binding affinity of stearic acid-trypsin, stearic acid-pepsin, and stearamide-pepsin was –22.51 kJ/mol, −12.35 kJ/mol, −19.28 kJ/mol respectively, which consistent with the trend in the enzyme activity results. This study can provide references for the selection of milk packaging materials and the use of processing additives, ensuring food health and safety.

Effect of three unsaturated fatty acids on the protein oxidation and structure of myofibrillar proteins from rainbow trout (Oncorhynchus mykiss)

In this study, the impact of three unsaturated fatty acids (Oleic acid: OA, Eicosapentaenoic acid: EPA, Docosahexaenoic acid: DHA) on the oxidation and structure of rainbow trout myofibrillar protein (MP) was explored. The findings revealed a notable increase in carbonyl content (P < 0.05) and a significant decrease in total sulfhydryl content (P < 0.05) of MP with the concentration increase of the three unsaturated fatty acids. Endogenous fluorescence spectroscopy and surface hydrophobicity analyses showed that unsaturated fatty acids can cause unfolding and exposure of hydrophobic groups in MP. In addition, SDS-PAGE showed that disulfide bonds were associated with MP cross-linking and aggregate size induced by unsaturated fatty acids. Overall, three unsaturated fatty acid treatments facilitated the oxidation of myofibrillar proteins, and the extent of protein oxidation was closely associated with the concentration of unsaturated fatty acids.