title: Identification and characterisation of the IgE-binding proteins 2S albumin and conglutin gamma in almond (Prunus dulcis) seeds.
abstract: BACKGROUND
  Almond proteins can cause severe anaphylactic reactions in susceptible individuals. The aim of this study was the identification of IgE-binding proteins in almonds and the characterisation of these proteins by N-terminal sequencing.
  
  
  METHODS
  Five sera were selected from individuals with a positive reaction to food challenge. Sodium dodecylsulphate-polyacrylamide gel electrophoresis and immunoblotting were performed on almond seed proteins. Purified IgE-binding proteins were tested for immunoblot inhibition with sera pre-incubated with extracts of hazelnut and walnut.
  
  
  RESULTS
  N-terminal sequences of the 12-, 30- and 45-kD proteins were obtained. The 45- and 30-kD proteins shared the same N terminus, with 60% homology to the conglutin gamma heavy chain from lupine seed (Lupinus albus) and to basic 7S globulin from soybean (Glycine max). The sequences of the N-terminal 12-kD protein and of an internal peptide obtained by endoproteinase digestion showed good homology to 2S albumin from English walnut (Jug r 1). Immunoblot inhibition experiments were performed and IgE binding to almond 2S albumin and conglutin gamma was detected in the presence of cross-reacting walnut or hazelnut antigens.
  
  
  CONCLUSIONS
  Two IgE-binding almond proteins were N-terminally sequenced and identified as almond 2S albumin and conglutin gamma. Localisation and conservation of IgE binding in a 6-kD peptide obtained by endoproteinase digestion of 2S albumin was shown.
authors.affiliation: Istituto di Ricerca sulle Biotecnologie Agroalimentari, CNR, Lecce, Italy. palmiro.poltronieri@irba.le.cnr.it
authors.forename: P
authors.initials: P
authors.lastname: Poltronieri
authors.forename: M S
authors.initials: MS
authors.lastname: Cappello
authors.forename: N
authors.initials: N
authors.lastname: Dohmae
authors.forename: A
authors.initials: A
authors.lastname: Conti
authors.forename: D
authors.initials: D
authors.lastname: Fortunato
authors.forename: E A
authors.initials: EA
authors.lastname: Pastorello
authors.forename: C
authors.initials: C
authors.lastname: Ortolani
authors.forename: G
authors.initials: G
authors.lastname: Zacheo
mesh_terms: D000418:Albumins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005512:Food Hypersensitivity / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D027861:Prunus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D012639:Seeds / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid
chemical_list: D000418:Albumins; D010940:Plant Proteins; C079483:conglutin-gamma protein, Lupinus angustifolius; D007073:Immunoglobulin E