Label-free based proteomics revealed the specific changes of muscle proteins in pike eel (Muraenesox cinereus) under cold stress

Study on peanut protein oxidation and metabolomics/proteomics analysis of peanut response under hypoxic/re-aeration storage

To better understand the effect of oxygen levels in the storage environment on peanut protein oxidation and explore the mechanism, the functional properties and the oxidation degree of peanut proteins extracted from peanuts under conventional storage (CS), nitrogen modified atmosphere storage (NS, hypoxic) and re-aeration storage (RS) were investigated. Metabolomics and proteomics were employed to analyze peanut's response to hypoxic/re-aeration storage environment. The results showed that NS retarded the decline of the functional properties and the oxidation of peanut proteins, while the process were accelerated after re-aeration. That was the result of the metabolic changes of peanuts under different storage environments. The omics results presented the decreased (NS)/increased (RS) levels of the antioxidant-related proteins acetaldehyde dehydrogenase and glutathione S-transferase, and the inhibition (NS)/activation (RS) of metabolic pathways such as the TCA cycle and the pentose phosphate pathway. This study provided a reference for the re-aeration storage of other agricultural products.

Spectrophotometric- and LC/MS-Based Lipidomics Analyses Revealed Changes in Lipid Profiles of Pike Eel (Muraenesox cinereus) Treated with Stable Chlorine Dioxides and Vacuum-Packed during Chilled Storage

Spectrophotometric- and liquid chromatography/mass spectrometry (LC/MS)-based lipidomics analyses were performed to explore the changes of lipid profiles in pike eel (Muraenesox cinereus) under stable chlorine dioxides (ClO₂) and vacuum-packed treatment during chilled storage. The peroxide value (PV) and malondialdehyde (MDA) content in ClO₂ treated and vacuum-packaged (VP) samples were significantly reduced compared to simple-packaged (SP) samples during whole chilled storage. The LC/MS-based lipidomics analyses identified 2182 lipid species in the pike eel muscle classified into 39 subclasses, including 712 triglycerides (TGs), 310 phosphatidylcholines (PCs), 153 phosphatidylethanolamines (PEs), and 147 diglycerides (DGs), among others. Further, in comparison with fresh pike eel (FE) muscle, 354 and 164 higher and 420 and 193 lower abundant levels of differentially abundant lipids (DALs) were identified in SP samples and VP samples, respectively. Compared with the VP batch, 396 higher and 404 lower abundant levels of DALs were identified in the SP batch. Among these, PCs, PEs, TGs, and DGs were more easily oxidized/hydrolyzed, which could be used as biomarkers to distinguish FE, SP, and VP samples. This research provides a reference for controlling lipid oxidation in fatty fish.

Cold-induced denaturation of muscle proteins in hairtail (Trichiurus lepturus) during storage: Physicochemical and label-free based proteomics analyses

Physicochemical, proteomics, and bioinformatics analyses were conducted to investigate protein profiles in Trichiurus haumela under frozen (120 d) and chilled (6 d) storage. Springiness, chewiness, myofibrillar active sulfhydryl content, and Ca²⁺-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.

Bioinformatic Prediction and Characterization of Proteins in Porphyra dentata by Shotgun Proteomics

Porphyra dentata is an edible red seaweed with high nutritional value. It is widely cultivated and consumed in East Asia and has vast economic benefits. Studies have found that P. dentata is rich in bioactive substances and is a potential natural resource. In this study, label-free shotgun proteomics was first applied to identify and characterize different harvest proteins in P. dentata. A total of 13,046 different peptides were identified and 419 co-expression target proteins were characterized. Bioinformatics was used to study protein characteristics, functional expression, and interaction of two important functional annotations, amino acid, and carbohydrate metabolism. Potential bioactive peptides, protein structure, and potential ligand conformations were predicted, and the results suggest that bioactive peptides may be utilized as high-quality active fermentation substances and potential targets for drug production. Our research integrated the global protein database, the first time bioinformatic analysis of the P. dentata proteome during different harvest periods, improves the information database construction and provides a framework for future research based on a comprehensive understanding.