In vitro digestion of major allergen in salmon roe and its peptide portion with proteolytic resistance

A fish yolk protein, β′-component (β′-c), is the major allergen in chum salmon roe. The effect of proteolysis on the allergenicity of β′-c was estimated. Changes in the IgE-binding ability of β′-c upon pepsin and trypsin digestion were investigated by monitoring the proteolytic cleavage. In the pepsin–trypsin digestion of chum salmon yolk protein, the β′-c contained therein was degraded in a manner similar to that of other yolk proteins, but digestion fragments with a molecular mass of >10 kDa remained throughout the digestion process. Specifically, the peptide sequence between 31-Y and 119-Q (10 kDa) was stable to pepsin–trypsin digestion and the portion showed high IgE-binding ability. As a result, pepsin–trypsin digestion had little effect on the IgE-binding ability of β′-c. These results suggest that β′-c reaches the small intestine in the form of high-molecular-mass components with IgE-binding ability in vivo.