Major shrimp allergen peptidomics signatures and potential biomarkers of heat processing

Effects of high voltage pulsed electric field on structural properties and immune reactivity of arginine kinase in Fenneropenaeus chinensis

To evaluate the effect of high voltage pulsed electric field (PEF) treatment (10-20 kV/cm, 5-15 min) on the structural characteristics and sensitization of crude extracts of arginine kinase from Fenneropenaeus chinensis. By simulated in vitro gastric juice digestion (SGF), intestinal juice digestion (SIF) and enzyme-linked immunosorbent assay (ELISA), AK sensitization was reduced by 42.5% when treated for 10 min at an electric field intensity of 15 kV/cm. After PEF treatment, the α-helix content decreased, and the α-helix content gradually changed to β-sheet and β-turn. Compared to the untreated group, the surface hydrophobicity increased and the sulfhydryl content decreased. SEM and AFM analyses showed that the treated sample surface formed a dense porous structure and increased roughness. The protein content, dielectric properties, and amino acid content of sample also changed significantly with the changes in the treatment conditions. Non-thermal PEF has potential applications in the development of hypoallergenic foods.

Quantification of Allergic Crustacean Tropomyosin Using Shared Signature Peptides in Processed Foods with a Mass Spectrometry-Based Proteomic Strategy

Crustacean shellfish are major allergens in East Asia. In the present study, a major allergic protein in crustaceans, tropomyosin, was detected accurately using multiple reaction monitoring mode-based mass spectrometry, with shared signature peptides identified through proteomic analysis. The peptides were deliberately screened through thermal stability and enzymatic digestion efficiency to improve the suitability and accuracy of the developed method. Finally, the proposed method demonstrated a linear range of 0.15 to 30 mgTM/kgfood (R2 > 0.99), with a limit of detection of 0.15 mgTM/kg food and a limit of quantification of 0.5mgTM/kgfood and successfully applied to commercially processed foods, such as potato chips, biscuits, surimi, and hot pot seasonings, which evidenced the applicability of proteomics-based methodology for food allergen analysis.

Assessing and Comparing Potential Allergenicity of Two Partially Hydrolyzed Whey-Based Formulas for Infants: A Population-Based Study in China

SCOPE

In cases where breast milk is unavailable or inadequate, hydrolyzed infant formula is recommended as the primary alternative. The aim of this study is to assess and compare the allergenicity of two partially hydrolyzed whey-based formulas (PHF-Ws) using serum samples from patients with cow's milk allergy (CMA).

METHODS AND RESULTS

LC-MS/MS technology is used to investigate the peptide distribution in both samples. The immunoreactivity of two PHF-Ws in 27 serum samples from 50 Chinese infants (02 years) with CMA is analyzed. The results demonstrate that even with a similar a degree of hydrolysis (DH), primary protein sources, peptides with molecular weights <5 kDa, and differences in the number of residual allergenic epitopes in the hydrolyzed peptide segments can lead to varying immune responses.

CONCLUSION

The two PHF-Ws have notably high intolerance rates, exceeding 10% among infants with CMA. Therefore, suggesting that PHF-Ws may not be suitable for infants and children with CMA in China.

Data-Independent Acquisition Peptidomics

In recent years, data-independent acquisition (DIA) has emerged as a powerful analysis method in biological mass spectrometry (MS). Compared to the previously predominant data-dependent acquisition (DDA), it offers a way to achieve greater reproducibility, sensitivity, and dynamic range in MS measurements. To make DIA accessible to non-expert users, a multifunctional, automated high-throughput pipeline DIAproteomics was implemented in the computational workflow framework "Nextflow" ( https://nextflow.io ). This allows high-throughput processing of proteomics and peptidomics DIA datasets on diverse computing infrastructures. This chapter provides a short summary and usage protocol guide for the most important modes of operation of this pipeline regarding the analysis of peptidomics datasets using the command line. In brief, DIAproteomics is a wrapper around the OpenSwathWorkflow and relies on either existing or ad-hoc generated spectral libraries from matching DDA runs. The OpenSwathWorkflow extracts chromatograms from the DIA runs and performs chromatographic peak-picking. Further downstream of the pipeline, these peaks are scored, aligned, and statistically evaluated for qualitative and quantitative differences across conditions depending on the user's interest. DIAproteomics is open-source and available under a permissive license. We encourage the scientific community to use or modify the pipeline to meet their specific requirements.

A systematic review on the recent advances of wheat allergen detection by mass spectrometry: future prospects

Wheat is one of the three major staple foods in the world. Although wheat is highly nutritional, it has a variety of allergenic components that are potentially fatal to humans and pose a significant hazard to the growth and consumption of wheat. Wheat allergy is a serious health problem, which is becoming more and more prevalent all over the world. To address and prevent related health risks, it is crucial to establish precise and sensitive detection and analytical methods as well as an understanding of the structure and sensitization mechanism of wheat allergens. Among various analytical tools, mass spectrometry (MS) is known to have high specificity and sensitivity. It is a promising non immune method to evaluate and quantify wheat allergens. In this article, the current research on the detection of wheat allergens based on mass spectrometry is reviewed. This review provides guidance for the further research on wheat allergen detection using mass spectrometry, and speeds up the development of wheat allergen research in China.

Site-specific labeling of antibodies with quantum dots could promote to retain the antigen binding capacity of antibodies

A major concern with antibody labeling is the decreased antigen affinity binding capacity of antibodies, owing mainly to the randomly oriented binding of the marker. Herein, a universal approach for site-specific photocrosslinking of quantum dots (QDs) to the Fc-terminal of antibodies was investigated utilizing antibody Fc-terminal affinity proteins. Results showed that the QDs only bound to the heavy chain of the antibody. Further comparative tests confirmed that the site-specific directed labeling approach maximizes the retention of the antigen-binding capacity of the natural antibody. Compared with the commonly employed random orientation labeling approach, the directional labeling approach allows the labeled antibody showed 6 times greater binding affinity to antigen. QDs-labeled monoclonal antibodies were applied to fluorescent immunochromatographic test strips for the detection of shrimp tropomyosin (TM). The established procedure has a detection limit of 0.054 μg/mL. Thus, the site-specific labeling approach significantly improves the antigen binding capacity of the labeled antibody.

Reduced Allergenicity of Shrimp (Penaeus vannamei) by Altering the Protein Fold, Digestion Susceptibility, and Allergen Epitopes

The mechanism by which thermal/pressure processing influences the allergenicity of shrimp (Penaeus vannamei) was explored by anaphylaxis in mice, the protein structure, gastrointestinal digestion, and linear epitopes. Roasting induced the unfolding of the structure, which may reduce the allergenicity, but it made more linear epitopes to be exposed, causing mice to exhibit similar systemic anaphylaxis as mice fed with the raw shrimp protein (p > 0.05). However, the roasted + reverse-pressure-sterilized shrimp can significantly reduce specific antibodies, mast cell degranulation, vascular permeability, and histopathological morphology in mice compared with the raw and roasted shrimp (p < 0.05) because reverse-pressure sterilization causes protein to aggregate, hiding the heat/digested stable epitopes of arginine kinase (Glu59-Ser63, Asn112-Lys118, Leu131-Phe136, and Ser158-Glu162) and sarcoplasmic calcium-binding protein (Asn57-Phe67, Ser159-Cys165, and Glu126-Ala130) inside a 3D structure, while gastrointestinal digestion can destroy immunodominant, minor epitopes and the epitopes exposed by roasting. Meanwhile, the low binding frequency of IgE to troponin C was also responsible for maintaining the hypoallergenicity of shrimp.

The alteration of composition, conformation, IgE-reactivity and functional attributes in proanthocyanidins-soy protein 7S conjugates formed by alkali-heating treatment: Multi-spectroscopic and proteomic analyses

This study assessed the alteration of IgE-reactivity and functional attribute in soy protein 7S-proanthocyanidins conjugates (7S-80PC) formed by alkali-heating treatment (pH 9.0, 80 °C, 20 min). SDS-PAGE demonstrated that 7S-80PC exhibited the formation of >180 kDa polymers, although the heated 7S (7S-80) had no changes. Multispectral experiments revealed more protein unfolding in 7S-80PC than in 7S-80. Heatmap analysis showed that 7S-80PC showed more alteration of protein, peptide and epitope profiles than 7S-80. LC/MS-MS demonstrated that the content of total dominant linear epitopes was increased by 11.4 % in 7S-80, but decreased by 47.4 % in 7S-80PC. As a result, Western-blot and ELISA showed that 7S-80PC exhibited lower IgE-reactivity than 7S-80, probably because 7S-80PC exhibited more protein-unfolding to increase the accessibility of proanthocyanidins to mask and destroy the exposed conformational epitopes and dominant linear epitopes induced by heating treatment. Furthermore, the successful attachment of PC to soy 7S protein significantly increased antioxidant activity in 7S-80PC. 7S-80PC also showed higher emulsion activity than 7S-80 owing to its high protein flexibility and protein unfolding. However, 7S-80PC exhibited lower foaming properties than 7S-80. Therefore, the addition of proanthocyanidins could decrease IgE-reactivity and alter the functional attribute of the heated soy 7S protein.

Peptidomics

Peptides are biopolymers, typically consisting of 2-50 amino acids. They are biologically produced by the cellular ribosomal machinery or by non-ribosomal enzymes and, sometimes, other dedicated ligases. Peptides are arranged as linear chains or cycles, and include post-translational modifications, unusual amino acids and stabilizing motifs. Their structure and molecular size render them a unique chemical space, between small molecules and larger proteins. Peptides have important physiological functions as intrinsic signalling molecules, such as neuropeptides and peptide hormones, for cellular or interspecies communication, as toxins to catch prey or as defence molecules to fend off enemies and microorganisms. Clinically, they are gaining popularity as biomarkers or innovative therapeutics; to date there are more than 60 peptide drugs approved and more than 150 in clinical development. The emerging field of peptidomics comprises the comprehensive qualitative and quantitative analysis of the suite of peptides in a biological sample (endogenously produced, or exogenously administered as drugs). Peptidomics employs techniques of genomics, modern proteomics, state-of-the-art analytical chemistry and innovative computational biology, with a specialized set of tools. The complex biological matrices and often low abundance of analytes typically examined in peptidomics experiments require optimized sample preparation and isolation, including in silico analysis. This Primer covers the combination of techniques and workflows needed for peptide discovery and characterization and provides an overview of various biological and clinical applications of peptidomics.

Enhancing the AI-2/LuxS quorum sensing system in Lactiplantibacillus plantarum: Effect on the elimination of biofilms grown on seafoods

The biofilm clustered with putrefying microorganisms and seafood pathogens could cover the surface of aquatic products that pose a risk to cross-contaminating food products or even human health. Fighting biofilms triggers synchronous communication associated with microbial consortia to regulate their developmental processes, and the enhancement of the quorum sensing system in Lactiplantibacillus plantarum can serve as an updated starting point for antibiofilm-forming strategies. Our results showed that the exogenous 25 mM L-cysteine induced a significant strengthening in the AI-2/LuxS system of Lactiplantibacillus plantarum SS-128 along with a stronger bacteriostatic ability, resulting in an effective inhibition of biofilms formed by the simplified microbial consortia constructed by Vibrio parahaemolyticus and Shewanella putrefaciens grown on shrimp and squid surfaces. The accumulation of AI-2 allowed the suppression of the expression of biofilm-related genes in V. parahaemolyticus under the premise of L. plantarum SS-128 treatment, contributing to the inhibition effect. In addition, strengthening the AI-2/LuxS system is also conducive to eliminating preexisting biofilms by L. plantarum SS-128. This study suggests that the enhancement of the AI-2/LuxS system of lactic acid bacteria enables the regulation of interspecific communication within biofilms to be a viable tool to efficiently reduce and eradicate potentially harmful biofilms from aquatic product sources, opening new horizons for combating biofilms.

Effects of methylglyoxal on shrimp tropomyosin structure and allergenicity during thermal processing

This study aimed to analyze the effect of methylglyoxal (MGO) on the structure and allergenicity of shrimp tropomyosin (TM) during thermal processing. The structural changes were determined by SDS-PAGE, intrinsic fluorescence, circular dichroism, and HPLC-MS/MS. The allergenicity was evaluated by in vitro and in vivo experiments. MGO could cause conformational structural changes in TM during thermal processing. Moreover, the Lys, Arg, Asp, and Gln residues of TM were modified by MGO, which could destroy and/or mask TM epitopes. In addition, TM-MGO samples could lead to lower mediators and cytokines released from RBL-2H3 cells. In vivo, TM-MGO caused a significant reduction in antibodies, histamine, and mast cell protease 1 levels in sera. These results indicate that MGO can modify the allergic epitopes and reduce the allergenicity of shrimp TM during thermal processing. The study will help to understand the changes in the allergenic properties of shrimp products during thermal processing.