Structure characterization and IgE-binding of soybean 7S globulin after enzymatic deglycosylation

Abstract

This study investigated the effects of enzymatic deglycosylation following ultrasound pretreatment on structure and immunoreactivity of soybean 7S globulin. Soybean 7S globulin was pretreated by ultrasound (40 kHz, 300 W) and enzymatically deglycosylated by peptide-N-glycosidase F (PNGase F). Changes in structure of processed soybean 7S globulin were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, reversed-phase high-performance liquid chromatography, ultraviolet absorption spectrum, circular dichroism spectrum, and surface hydrophobicity analysis. Enzyme-linked immunoabsorbent assay was used to evaluate IgE-binding ability. The results showed that the glycan moieties of soybean 7S globulin were effectively removed by PNGase F, which significantly modified protein structures including the secondary and tertiary structures of 7S globulin. Individual enzymatic deglycosylation could reduce IgE-binding capacity of 7S globulin, whereas enzymatic deglycosylation following ultrasound pretreatment enhanced its IgE-binding capacity. In conclusion, soybean 7S globulin treated by single enzymatic deglycosylation can reduce potential allergenicity and may be employed in hypoallergenic food preparation.

Keywords

• Soybean 7S globulin
• Enzymatic deglycosylation
• Ultrasound pretreatment
• Protein structure
• IgE-binding