title: In vitro digestion of soluble cashew proteins and characterization of surviving IgE-reactive peptides.
abstract: METHODS
  The stability of food allergens to digestion varies. We characterized the stability of cashew allergens to digestion by pepsin and trypsin and identified IgE-binding epitopes that survive digestion.
  
  
  RESULTS
  The ability of pepsin and trypsin to digest cashew allergens was assessed with an in vitro digestion model. Samples were evaluated by SDS-PAGE, MS, ELISA, and immunoblotting to compare IgE binding. Increasing amount of protease resulted in greater degradation of higher molecular weight cashew proteins. Among cashew proteins, the 2S albumin, Ana o 3, was most resistant to digestion by both pepsin and trypsin. MS identified digestion resistant Ana o 3 protein fragments that retained reported IgE-binding epitopes. Pretreatment of extracts or purified Ana o 3 with reducing agent increased the sensitivity of Ana o 3 to protease digestion. Circular dichroism revealed the structure of purified Ana o 3 was largely alphahelical and was disrupted following reduction. Ana o 3 reduction followed by protease digestion decreased binding of serum IgE from cashew allergic patients. Our results indicate that the Ana o 3 disulfide bond dependent structure protects the protein from proteolysis.
  
  
  CONCLUSIONS
  Ana o 3 is the cashew allergen most likely to survive gastrointestinal digestion intact.
authors: U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, USA.
authors: Christopher P
authors: CP
authors: Mattison
authors: Casey C
authors: CC
authors: Grimm
authors: Richard L
authors: RL
authors: Wasserman
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D031021:Anacardium / Q000737:chemistry; D052179:Antigens, Plant / Q000276:immunology* / Q000378:metabolism; D002648:Child; D004063:Digestion; D000939:Epitopes / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D008875:Middle Aged; D008969:Molecular Sequence Data; D021184:Nut Hypersensitivity / Q000097:blood / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology* / Q000378:metabolism; D012995:Solubility; D055815:Young Adult
chemical_list: C502483:Ana o 3 protein, Anacardium occidentale; D052179:Antigens, Plant; D000939:Epitopes; D010940:Plant Proteins; D007073:Immunoglobulin E
keywords: Allergen; Cashew; Digestion; Pepsin; Trypsin