Purification, characterization and immunoreactivity of tropomyosin, the allergen in Octopus fangsiao

Effect of the Combined Ultrasound with Other Technologies on Food Allergenicity: Ultrasound before, under, and after Other Technologies

Food allergies are a main public health disease in the world. Ultrasound is an environmentally friendly technology that typically leads to protein unfolding and loss of protein structure, which means it has the potential to be combined with other technologies to achieve a great reduction of allergenicity in foods. This review concludes the effects of the combined ultrasound with other technologies on food allergenicity from three combinations: ultrasound before other technologies, ultrasound under other technologies, and ultrasound after other technologies. Each combination affects food allergenicity through different mechanisms: (1) as for ultrasound before other technologies, ultrasound pretreatment can unfold and lose the protein structure to improve the accessibility of other technologies to epitopes; (2) as for ultrasound under other technologies, ultrasound can continuously affect the accessibility of other technologies to epitopes; (3) as for ultrasound after other technologies, ultrasound further induces structural changes to mask and disrupt the epitopes. The reduction of allergenicity is related to the ultrasound/other technologies conditions and food types/cultivars, etc. The comparison of ultrasound before, under, and after other technologies to decrease food allergenicity should be further investigated in the future. The combination of ultrasound with other technologies is promising to produce hypoallergenic foods.

Effect of thermal and ultrasound treatments on denaturation and allergenic potential of Pru p 3 protein from peach

The effect of thermal and ultrasound treatments on denaturation and allergenicity of Pru p 3, the major peach allergenic protein, was determined. The degree of denaturation of Pru p 3 was estimated by sandwich ELISA using specific rabbit IgG, that was previously developed. Validation of ELISA test showed high sensitivity and specificity, and acceptable results of precision and robustness. Allergenicity of Pru p 3 was determined by immunofluorescent assay using three pools of sera from peach allergic individuals. Denaturation of Pru p 3 was dependent on the intensity of the thermal treatment applied and the treatment medium. Thus, the degree of denaturation of Pru p 3 treated at 95 °C for 40 min was about 60% and 95%, for the protein heated in peach extract and in buffer, respectively. Ultrasound treatments denatured Pru p 3 up to 60%, being dependent on amplitude and pressure. However, both heat and ultrasound treatments at the most severe conditions applied inhibited less than 10% the IgE-binding of Pru p 3. These results indicate that although heat and ultrasound treatments induce a considerable denaturation of Pru p 3, they are not effective in reducing its allergenicity.

Graphical abstract

Identification of linear epitopes and their major role in the immunoglobulin E-binding capacity of tropomyosin from Alectryonella plicatula

Tropomyosin (TM) is an important allergen in molluscans. However, there was a lack of information about TM as an allergen in oysters. TM was purified and identified from Alectryonella plicatula (ATM), and its primary sequence was cloned and encoded with 284 amino acids (AAs). Chemical denaturants were used to destroy the structure to confirm that linear epitopes played a major role in the immunoglobulin E-binding capacity of ATM. Subsequently, nine linear epitopes were identified using a serological test. The peptide with AA_27-41 was regarded as the key epitope because it could be recognized strongly by most sera of oyster-sensitive individuals in comparison to other epitope peptides. Finally, the epitopes and the primary sequence of TM among shellfish were aligned to find the two conserved epitopes (AA_117-132 and AA_164-178) in oyster, octopus, abalone, scallop, clam, shrimp, and crab. Overall, these data provide a foundation for the allergenicity and cross-reactivity of TM.

An overview of tropomyosin as an important seafood allergen: Structure, cross-reactivity, epitopes, allergenicity, and processing modifications

Tropomyosin (TM) is a major allergen in crustaceans, which often causes allergy and is fatal to some consumers. Currently, the most effective treatment is to avoid ingesting TM, although most adverse events occur in accidental ingestion. In this review, the molecular characterization, epitopes, cross-reactivity, and pathogenesis of TM are introduced and elucidated. Modification of TM by traditional processing methods such as heat treatment and enzymatic hydrolysis, and innovative processing technologies including high-pressure treatment, cold plasma (CP), ultrasound, pulsed electric field (PEF), pulsed ultraviolet, microwave and irradiation are discussed in detail. Particularly, enzymolysis, PEF, and CP technologies show great potential for modifying TM and more studies are needed to verify their effectiveness for the seafood industry. Possible mechanisms and the advantages/disadvantages of these technologies for the mitigation of TM allergenicity are also highlighted. Further work should be conducted to investigate the allergenicity caused by protein segments such as epitopes, examine the interaction sites between the allergen and the processing techniques and reveal the reduction mechanism of allergenicity.

Boronic acid-functionalized agarose affinity chromatography for isolation of tropomyosin in fishes

BACKGROUND

Tropomyosin is now receiving increasing attention because of its significant allergenic activity in various fishery products but its simple and effective isolation still remains a challenging task.

RESULTS

An agarose-based boronate affinity chromatography was produced for the first time to isolate tropomyosin in various fishery products using 3,5-difluoro-4-formyl-phenylboronic acid as the functional monomer, tris(2-aminoethyl)amine as the multi-branched ligand, and agarose gel particles as supporting materials. The agarose concentration, binding pH, and the concentration of elution buffers demonstrated significant effects on separation performance. Under optimized conditions, the purity of the isolated tropomyosin was higher than 90%, with the column adsorption capacity over 1.85 mg mL^-1 and the enrichment efficiency over 65%. Such efficiency was also validated with different fish samples including Paralichthys olivaceus, Thunnusthynnus, Oreochromis spp., and Lophius litulon.

CONCLUSION

In comparison with conventional methods, the established affinity chromatography demonstrated excellent biocompatibility (without involving any organic solvent), better speed (from at least 1-2 days to 3-4 h), and simplicity (from at least five steps to three steps). This suggests that it is a novel and promising technique for the isolation of tropomyosin and other glycoproteins (including most allergens) in foodstuffs. © 2019 Society of Chemical Industry.

Novel calcium-chelating peptides from octopus scraps and their corresponding calcium bioavailability

BACKGROUND

To reducing the massive marine pollution and resource waste caused by octopus scraps, we developed a novel octopus scraps protein hydrolysate (OSPH), which displays calcium-chelating activity, and we investigated the chelating interaction and calcium bioavailability of OSPH-Ca.

RESULTS

The structural properties of amido and carboxy groups indicated that they could be the reaction sites for chelation. The particle radius of OSPH increased by 32.25 nm after the calcium chelated with OSPH, indicating intramolecular and intermolecular folding and aggregating. The enthalpy of OSPH increased by 0.8323 after chelation, showing that bands of OSPH-Ca needed more thermal energy to be destroyed than OSPH. Meanwhile, the chelate showed remarkable stability and absorbability under either acidic or basic conditions, which favored calcium absorption in the gastrointestinal tracts of humans. The calcium intake of OSPH-Ca increased by 41% when compared with that of CaCl₂ . In particular, OSPH-Ca could protect calcium ions from precipitation caused by dietary inhibitors tannic acid and phytate, while calcium uptake efficiency remained at 3.35 and 1.68 times higher than that of CaCl₂ .

CONCLUSION

These findings revealed the feasibility of transforming octopus scraps into a novel functional calcium chelate based on peptides, promoting environmental sustainability. © 2018 Society of Chemical Industry.

Triosephosphate Isomerase and Filamin C Share Common Epitopes as Novel Allergens of Procambarus clarkii

Triosephosphate isomerase (TIM) is a key enzyme in glycolysis and has been identified as an allergen in saltwater products. In this study, TIM with a molecular mass of 28 kDa was purified from the freshwater crayfish (Procambarus clarkii) muscle. A 90-kDa protein that showed IgG/IgE cross-reactivity with TIM was purified and identified as filamin C (FLN c), which is an actin-binding protein. TIM showed similar thermal and pH stability with better digestion resistance compared with FLN c. The result of the surface plasmon resonance (SPR) experiment demonstrated the infinity of anti-TIM polyclonal antibody (pAb) to both TIM and FLN c. Five linear and 3 conformational epitopes of TIM, as well as 9 linear and 10 conformational epitopes of FLN c, were mapped by phage display. Epitopes of TIM and FLN c demonstrated the sharing of certain residues; the occurrence of common epitopes in the two allergens accounts for their cross-reactivity.