Effects of temperature on protein phosphorylation in postmortem muscle

Correlation analysis of phosphorylation of myofibrillar protein and muscle quality of tilapia during storage in ice

In this study, the correlation between protein phosphorylation and deterioration in the quality of tilapia during storage in ice was examined by assessing changes in texture, water-holding capacity (WHC), and biochemical characteristics of myofibrillar protein throughout 7 days of storage. The hardness significantly decreased from 471.50 to 252.17 g, whereas cooking and drip losses significantly increased from 26.5% to 32.6% and 2.9% to 9.1%, respectively (P < 0.05). Myofibril fragmentation increased, while myofibrillar protein sulfhydryl content and Ca2+-ATPase activity decreased from 119.33 to 89.29 μmol/g prot and 0.85 to 0.46 μmolPi/mg prot/h, respectively (P < 0.05). Correlation analysis revealed that the myofibrillar protein phosphorylation level was positively correlated with hardness and Ca2+-ATPase activity but negatively correlated with WHC. Myofibrillar protein phosphorylation affects muscle contraction by influencing the dissociation of actomyosin, thereby regulating hardness and WHC. This study provides novel insights for the establishment of quality control strategies for tilapia storage based on protein phosphorylation.

Protein Post-Translational Modifications Based on Proteomics: A Potential Regulatory Role in Animal Science

Genomic studies in animal breeding have provided a wide range of references; however, it is important to note that genes and mRNA alone do not fully capture the complexity of living organisms. Protein post-translational modification, which involves covalent modifications regulated by genetic and environmental factors, serves as a fundamental epigenetic mechanism that modulates protein structure, activity, and function. In this review, we comprehensively summarize various phosphorylation and acylation modifications on metabolic enzymes relevant to energy metabolism in animals, including acetylation, succinylation, crotonylation, β-hydroxybutylation, acetoacetylation, and lactylation. It is worth noting that research on animal energy metabolism and modification regulation lags behind the demands for growth and development in animal breeding compared to human studies. Therefore, this review provides a novel research perspective by exploring unreported types of modifications in livestock based on relevant findings from human or animal models.

Effects of different protein phosphorylation levels on the tenderness of different ultimate pH beef

This study investigated the relationship between tenderness and protein phosphorylation levels of normal ultimate pH (pHu, 5.4-5.8, NpHu), intermediate pHu (5.8-6.2, IpHu) and high pHu (≥6.2, HpHu) Longissimus lumborum from beef. During 21 d of ageing, the HpHu group had the lowest Warner-Bratzler shear force (WBSF) values, while the IpHu group showed the highest and even after 21 days of ageing still had high levels. In the late stage of the 24 h post-mortem period the faster degradation rate of troponin T and earlier activation of caspase 9 in the HpHu group were the key reasons for the lower WBSF compared with the NpHu and IpHu groups. The activity of caspase 3 cannot explain the tenderness differences between IpHu and HpHu groups, since their activities did not show any difference. At 24 h post-mortem, 17 common differential phosphorylated peptides were detected among pHu groups, of which nine were associated with pHu and WBSF. The higher phosphorylation level of glycogen synthase may have caused the delay of meat tenderization in the IpHu group.

The effect of thermal times of circulating non-fried roast technique on the formation of (non)volatile compounds in roasted mutton by multi-chromatography techniques and heat transfer analysis

The circulating non-fried roast (CNR) technology was firstly applied to roast mutton. The formation of (non)volatile compounds in the mutton roasted for 0-15 min was investigated. The samples roasted at varying times were discriminated using GC-O-MS and multivariate data analysis. A total of 40 volatile compounds were observed, in which 17 compounds were considered as key odorants with odor activity values (OAVs) higher than 1, such as dimethyl trisulfide and 2-ethyl-3,5-dimethylpyrazine. Composition and concentrations of volatile compounds were significantly changed during the process. The key nonvolatile compounds that contributed to flavor were 5'-inosine monophosphate (5'-IMP) and glutamic acid based on taste active values (TAVs) greater than 1. The reduced concentrations of most free amino acids and 5'-nucleotides decreased the equivalent umami concentrations (EUC). The higher thermal conductivity, lower thermal diffusivity and water activity were responsible for the formation of volatile compounds with increased roasting times. The CNR technology was an efficient tool to roast meat products.

Protein Phosphorylation Induced by Pyruvate Kinase M2 Inhibited Myofibrillar Protein Degradation in Post-Mortem Muscle

Myofibrillar protein degradation is primarily related to meat tenderness through protein phosphorylation regulation. Pyruvate kinase M2 (PKM2), a glycolytic rate-limiting enzyme, is also regarded as a protein kinase to catalyze phosphorylation. The objective of this study was to investigate the relationship between myofibrillar protein degradation and phosphorylation induced by PKM2. Myofibrillar proteins were incubated with PKM2 at 4, 25, and 37 °C. The global phosphorylation level of myofibrillar proteins in the PKM2 group was significantly increased, but it was sensitive to temperature (P < 0.05). Compared with 4 and 25 °C, PKM2 significantly increased the myofibrillar protein phosphorylation level from 0.5 to 6 h at 37 °C (P < 0.05). In addition, the degradation of desmin and actin was inhibited after they were phosphorylated by PKM2 when incubated at 37 °C. These results demonstrate that phosphorylation of myofibrillar proteins catalyzed by PKM2 inhibited protein degradation and provided a possible pathway for meat tenderization through glycolytic enzyme regulation.

Phosphoproteomic insight into the changes in structural proteins of muscle architecture associated with texture softening of grass carp (Ctenopharyngodon idella) fillets during chilling storage

Texture is an important sensory attribute of fish affected by modifications of structural proteins in muscle architecture. To investigate the changes in protein phosphorylation during texture softening of fish, the proteins of grass carp muscle after chilling storage of 0 day and 6 days were compared by phosphoproteomics, and their association with texture was analyzed. Totally 1026 unique phosphopeptides on 656 phosphoproteins were identified as differential. They were mainly classified as intracellular myofibril and cytoskeleton, and extracellular matrix, of which the molecular function and biological process were binding into supramolecular assembly and myofilament contraction. The concomitant dephosphorylation of kinases and assembly regulators indicated dephosphorylation and disassembly tendency of sarcomeric architecture. Correlation analysis defined the relation between texture and dephosphorylation of myosin light chain, actin, collagen and cytoskeleton. This study revealed that protein phosphorylation may affect the texture of fish muscle through regulating sarcomeric assembly of structural proteins in muscle architecture.

Phosphorylation and acetylation responses of glycolytic enzymes in meat to different chilling rates

The aim of this study was to investigate the effects of chilling rate on phosphorylation and acetylation levels of the glycolytic enzymes in meat, including glycogen phosphorylase, phosphofructokinase, aldolase (ALDOA), triose-phosphate isomerase (TPI1), phosphoglycerate kinase, lactate dehydrogenase (LDH). The samples were assigned into three groups: Control, Chilling 1 and Chilling 2, corresponding to the chilling rates of 4.8 °C/h, 23.0 °C/h and 25.1 °C/h respectively. The contents of glycogen and ATP were significantly higher in samples from the chilling groups. The activity and phosphorylation level of the six enzymes were higher in samples at the chilling rate of 25.1 °C/h, while the acetylation level of ALDOA, TPI1 and LDH were inhibited. In brief, glycolysis was delayed and the activity of glycolytic enzymes were maintained at higher level by the changes of phosphorylation and acetylation levels at the chilling rates of 23.0 °C/h and 25.1 °C/h, which may partly explain why very fast chilling improves meat quality.

Organ-Based Proteome and Post-Translational Modification Profiling of a Widely Cultivated Tropical Water Fish, Labeo rohita

Proteomics has enormous applications in human and animal research. However, proteomic studies in fisheries science are quite scanty particularly for economically important species. Few proteomic studies have been carried out in model fish species, but comprehensive proteomics of aquaculture species are still scarce. This study aimed to perform a comprehensive organ-based protein profiling of important tissue samples for one of the most important aquaculture species,Labeo rohita.Deep proteomic profiling of 17 histologically normal tissues, blood plasma, and embryo provided mass-spectrometric evidence for 8498 proteins at 1% false discovery rate that make up about 26% of the total annotated protein-coding sequences in Rohu. Tissue-wise expression analysis was performed, and the presence of several biologically important proteins was also verified using a targeted proteomic approach. We identified the global post-translational modifications (PTMs) in terms of acetylation (N-terminus and lysine), methylation (N-terminus, lysine, and arginine), and phosphorylation (serine, threonine, and tyrosine) to present a comprehensive proteome resource. An interactive web-based portal has been developed for an overall landscape of protein expression across the studied tissues of Labeo rohita (www.fishprot.org). This draft proteome map of Labeo rohita would advance basic and applied research in aquaculture to meet the most critical challenge of providing food and nutritional security to an increasing world population.

Impact of Chilling Rate on the Evolution of Volatile and Non-Volatile Compounds in Raw Lamb Meat during Refrigeration

The aim of this study was to investigate the effect of chilling rate (1.44, 22.2, and 32.4 °C/h) on the evolution of volatile and non-volatile compounds in raw lamb meat during refrigeration (1, 24, 72, and 120 h). Through orthogonal projection to latent structure-discriminant analysis, the calculation of odor activity values (OAV > 1) and taste activity values (TAV > 1) analysis, 1-octen-3-ol, (E, E)-2,4-decadienal, nonanal, hexanal, nona-3,5-dien-2-one, 2,3-octanedione, hexanoic acid, 1-nonen-4-ol, aspartate (Asp), Glutamic Acid (Glu), 5′-GMP, 5′-IMP, and 5′-AMP were regarded as differential flavor or taste compounds for raw meat undergone different chilling rates. With a rapid chilling rate at 24 h after slaughter, the contribution of 1-octen-3-ol decreased, but (E, E)-2,4-decadienal increased. Moreover, at 24 h post-mortem, the equivalent umami concentration of Asp, Glu, 5′-GMP, 5′-IMP and 5′-AMP in raw meat were significantly lower at a chilling rate of 1.44 °C/h than 32.4 °C/h (p < 0.05). Conclusively, under the rapid chilling rate, more fatty odor and umami compounds accumulated in 24 h aged meat.

Effects of protein posttranslational modifications on meat quality: A review

Meat quality plays an important role in the purchase decision of consumers, affecting producers and retailers. The formation mechanisms determining meat quality are intricate, as several endogenous and exogenous factors contribute during antemortem and postmortem periods. Abundant research has been performed on meat quality; however, unexpected variation in meat quality remains an issue in the meat industry. Protein posttranslational modifications (PTMs) regulate structures and functions of proteins in living tissues, and recent reports confirmed their importance in meat quality. The objective of this review was to provide a summary of the research on the effects of PTMs on meat quality. The effects of four common PTMs, namely, protein phosphorylation, acetylation, S-nitrosylation, and ubiquitination, on meat quality were discussed, with emphasis on the effects of protein phosphorylation on meat tenderness, color, and water holding capacity. The mechanisms and factors that may affect the function of protein phosphorylation are also discussed. The current research confirms that meat quality traits are regulated by multiple PTMs. Cross talk between different PTMs and interactions of PTMs with postmortem biochemical processes need to be explored to improve our understanding on factors affecting meat quality.

Effects of roasting by charcoal, electric, microwave and superheated steam methods on (non)volatile compounds in oyster cuts of roasted lamb

This work was conducted to compare (non)volatile compounds and sensory evaluation of oyster cuts of roasted lamb. Three newer roasting methods, namely electrically heated air (EHA), microwave heat (MWH) and superheated steam (SHS), were compared with traditional burning charcoal (BCC). The results showed that the 3 new roasting methods all generated rich nonvolatile compounds and volatile compounds in samples, which was similar to the results of those prepared by BCC. Particularly, the EHA produced more nonvolatile compounds and higher equivalent umami concentrations than the other new methods, especially regarding umami amino acids. Moreover, the EHA and SHS methods had better sensory evaluations than the MWH, including acceptability, fat and roast flavours, and they had better odour activity values (OAVs) of characteristic volatile compounds, such as octanal, nonanal and (E, E)-2,4-decadienal. It was concluded that the EHA might be a potential method to replace the BCC due to our findings about nonvolatile compounds, OAVs of volatile compounds and sensory evaluation.

Role of phosphorylation on characteristics of glycogen phosphorylase in lamb with different glycolytic rates post-mortem

The relationship between glycogen phosphorylase activity and phosphorylation levels in the longissimus thoracis muscle post-mortem was studied. Sixty lamb samples were collected at 0.5 h, 2 h, 6 h, 12 h, 24 h, 48 h, and 72 h post-mortem and divided into three groups (n = 6) with different glycolytic rates (fast, intermediate, and slow) according to the pH at 6 h post-mortem. The phosphorylation level and activity and expression of glycogen phosphorylase were determined. The results showed that the phosphorylation level and activity of glycogen phosphorylase in the slow pH decline group was lower than that in the fast pH decline group during 24 h post-mortem (P < .05). There was a significant positive correlation between the glycogen phosphorylase activity and the phosphorylation level. In conclusion, these data demonstrated that the glycogen phosphorylase activity in lambs was affected by phosphorylation levels and postmortem duration.

Quantitative Comparative Integrated Proteomic and Phosphoproteomic Analysis of Chicken Egg Yolk Proteins under Diverse Storage Temperatures

To investigate the alterations of egg yolk protein abundances and their phosphorylation status at different storage temperatures, a comparative quantitative study of unfertilized chicken egg yolk after 15 days of storage at 4 and 37 °C was performed. Altogether, 445 proteins were identified in our study, of which the abundances of 154 proteins were significantly changed when comparing high-temperature storage with low-temperature storage, including 42 up-regulated and 112 down-regulated proteins. In the phosphoproteome, we identified a total of 137 phosphorylated sites on 326 peptides corresponding to 51 proteins. The results showed that the degree of phosphorylation for most egg yolk proteins was enhanced during high-temperature storage. Furthermore, GO analysis indicated that these phosphoproteins of egg yolk may be closely related to the binding, catalysis, and transport functions. The results provide further insights into the effect of storage temperature on egg proteome changes and their phosphorylation level. Moreover, this study can provide a theoretical basis for the improvement of egg quality during storage by phosphorylation modification in the food industry.