This research aims to investigate the solubility, structural properties, and immunomodulatory of rice dreg protein (RDP) modified with sodium alginate. The modification was done by wet heating assisted with microwave treatment. The solubility, emulsifying properties at pH 2–12, amino acid composition, molecular weight distribution, circular dichroism (CD) spectroscopy, and FTIR spectra of modified RDP were analyzed and discussed. Results showed that Maillard reaction could significantly enhance the solubility and emulsifying capacity of RDP. Further, an animal model for cyclophosphamide‐induced immunodeficiency was designed to evaluate the immunomodulatory effect of modified RDP. It is therefore suggested that modified RDP could improve the immunomodulatory effect of immunosuppressed mice, and the immunomodulation was concentration dependent, being generally enhanced by increased concentrations. This research revealed that glycosylation modification of RDP through Maillard reaction by wet heating assisted with microwave treatment may be successfully applied to improve the physicochemical properties and bioactive benefits of the final product.
Mannooligosaccharides
are released by mannan-degrading endo-β-1,4-mannanase
and are known as functional additives
in human and animal diets. To satisfy demands for biocatalysis and
bioprocessing in crowed environments, in this study, we employed a
recently developed enzyme-engineering system, isopeptide bond-mediated
molecular cyclization, to modify a mesophilic mannanase from Bacillus subtilis. The results revealed that the cyclized
enzymes showed enhanced thermostability and ion stability and resilience
to aggregation and freeze–thaw treatment by maintaining their
conformational structures. Additionally, by using the SpyTag/SpyCatcher
system, we generated a mannanase-xylanase bifunctional enzyme that
exhibited a synergistic activity in substrate deconstruction without
compromising substrate affinity. Interestingly, the dual-enzyme ring
conformation was observed to be more robust than the linear enzyme
but inferior to the single-enzyme ring conformation. Taken together,
these findings provided new insights into the mechanisms of molecular
cyclization on stability improvement and will be useful in the production
of new functional oligosaccharides and feed additives.
Parvalbumin (PV) induces IgE-mediated allergic reactions and is an important allergen in fish species. The effects of high hydrostatic pressure (HHP) treatment (300, 450, 600 MPa; 10 min) on the structural characteristics of PV in cultured large yellow croakers (Larimichthys crocea) were investigated. The effects of HHP treatment were analyzed by free sulfhydryl content, surface hydrophobicity, circular dichroism spectroscopy (CD), laser Raman spectroscopy, and endogenous fluorescence spectroscopy. The results showed that after HHP treatment, the free sulfhydryl content in PV decreased slightly and the surface hydrophobicity increased, indicating changes in the tertiary structure of PV. CD showed that with increase in pressure, the content of α-helix in the secondary structure of PV decreased slightly. This indicated that the stability of the secondary structure of PV was affected by HHP treatment. The secondary structure of PV was dominated by α-helix and that the α-helix content in PV also increased. The redshift of endogenous fluorescence spectroscopy decreases the fluorescence intensity. Practical applications Parvalbumin (PV) in the large yellow croaker is the main allergen with a molecular weight of 12 kDa. It is an allergy risk to consumers. The application of high hydrostatic pressure (HHP) treatment of 200 to 400 MPa could be successfully applied to changes of the tertiary and secondary structure of PV. This suggests a direct and important relationship between the structural characteristics and allergenicity of PV. The application of HHP treatment effectively reduced the allergenicity of PV. It is useful to desensitization of the large yellow croaker before processing. 1 | INTRODUC TI ON Fish are a key food resource of human populations worldwide, with the earliest aquaculture activities dating as far back as 3,500 BC. Approximately one-sixth of the world's protein intake is from fish, with the proportion being much high in certain developing countries and regions that depend heavily on oceans for food. The large yellow croaker (Larimichthys crocea), which belongs to the family Sciaenidae of the order Perciformes, is a warm-temperate demersal neritic fish species that exhibits schooling and migratory behaviors. How to cite this article: Zhang H, Liao H, Lu Y, et al. Effects of high hydrostatic pressure on the structural characteristics of parvalbumin of cultured large yellow croaker (Larimichthys crocea).
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