title: Responsiveness of the major birch allergen Bet v 1 scaffold to the gastric environment: impact on structure and allergenic activity.
abstract: METHODS
  Four Bet v 1 homologous food allergens from celeriac (rApi g 1), apple (rMal d 1), peach (rPru p 1) and hazelnut (rCor a 1), were used to probe the structural responsiveness of the Bet v 1 scaffold to gastric digestion conditions and its impact on allergenicity.
  
  
  RESULTS
  Low pH induced conformational changes of all homologues, which was reduced at physiological ionic strength for all except rPru p 1 as observed by circular dichroism (CD)-spectroscopy. The homologues were rapidly digested by pepsin, losing their IgE binding activity, although the kinetics and patterns of digestion varied subtly between homologues, rApi g 1 being the most stable. We have demonstrated for the first time that gastric phosphatidyl-choline (PC) induced conformational changes in all homologues but only rMal d 1 penetrated the PC vesicles as detected by fluorescence polarization, slowing its digestion and retaining more of its allergenic activity. PC enhanced basophil activation of all digested allergens except rApi g 1.
  
  
  CONCLUSIONS
  The Bet v 1 scaffold is generally susceptible to low pH and pepsinolysis and interacts with PC vesicles, properties which can explain effects of the gastric environment on their allergenicity. These data show the importance of including surfactants in model digestion systems.
authors.affiliation: Institute of Food Research, Norwich, UK. ana.sancho@sbg.ac.at
authors.forename: Ana I
authors.initials: AI
authors.lastname: Sancho
authors.forename: Andrea
authors.initials: A
authors.lastname: Wangorsch
authors.forename: Bettina M
authors.initials: BM
authors.lastname: Jensen
authors.forename: Andrew
authors.initials: A
authors.lastname: Watson
authors.forename: Yuri
authors.initials: Y
authors.lastname: Alexeev
authors.forename: Phil E
authors.initials: PE
authors.lastname: Johnson
authors.forename: Alan R
authors.initials: AR
authors.lastname: Mackie
authors.forename: Angela
authors.initials: A
authors.lastname: Neubauer
authors.forename: Gerald
authors.initials: G
authors.lastname: Reese
authors.forename: Barbara
authors.initials: B
authors.lastname: Ballmer-Weber
authors.forename: Karin
authors.initials: K
authors.lastname: Hoffmann-Sommergruber
authors.forename: Per S
authors.initials: PS
authors.lastname: Skov
authors.forename: Stefan
authors.initials: S
authors.lastname: Vieths
authors.forename: Elisabeth N Clare
authors.initials: EN
authors.lastname: Mills
mesh_terms: D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000937:Antigen-Antibody Reactions; D052179:Antigens, Plant / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015549:Basophil Degranulation Test; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D005512:Food Hypersensitivity / Q000276:immunology*; D005750:Gastric Juice / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007073:Immunoglobulin E / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D010434:Pepsin A / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D017433:Protein Structure, Secondary; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000378:metabolism
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D010713:Phosphatidylcholines; D010940:Plant Proteins; D011994:Recombinant Proteins; D013501:Surface-Active Agents; D053835:Unilamellar Liposomes; C539117:rBet v 1a Mut1-6 allergen, birch; D007073:Immunoglobulin E; D010434:Pepsin A; D004134:Dimyristoylphosphatidylcholine