title: Enzymatic activity and immunoreactivity of Aca s 4, an alpha-amylase allergen from the storage mite Acarus siro.
abstract: BACKGROUND
  Enzymatic allergens of storage mites that contaminate stored food products are poorly characterized. We describe biochemical and immunological properties of the native alpha-amylase allergen Aca s 4 from Acarus siro, a medically important storage mite.
  
  
  RESULTS
  A. siro produced a high level of alpha-amylase activity attributed to Aca s 4. This enzyme was purified and identified by protein sequencing and LC-MS/MS analysis. Aca s 4 showed a distinct inhibition pattern and an unusual alpha-amylolytic activity with low sensitivity to activation by chloride ions. Homology modeling of Aca s 4 revealed a structural change in the chloride-binding site that may account for this activation pattern. Aca s 4 was recognized by IgE from house dust mite-sensitive patients, and potential epitopes for cross-reactivity with house dust mite group 4 allergens were found.
  
  
  CONCLUSIONS
  We present the first protein-level characterization of a group 4 allergen from storage mites. Due to its high production and IgE reactivity, Aca s 4 is potentially relevant to allergic hypersensitivity.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 16610 Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Pytelková
authors.forename: Martin
authors.initials: M
authors.lastname: Lepšík
authors.forename: Miloslav
authors.initials: M
authors.lastname: Sanda
authors.forename: Pavel
authors.initials: P
authors.lastname: Talacko
authors.forename: Lucie
authors.initials: L
authors.lastname: Marešová
authors.forename: Michael
authors.initials: M
authors.lastname: Mareš
mesh_terms: D040041:Acaridae / Q000201:enzymology* / Q000276:immunology; D000485:Allergens / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D003429:Cross Reactions; D005243:Feces / Q000737:chemistry; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D019476:Insect Proteins / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D000516:alpha-Amylases / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000485:Allergens; D019476:Insect Proteins; D007073:Immunoglobulin E; D000516:alpha-Amylases