Enzymatic activity and immunoreactivity of Aca s 4, an alpha-amylase allergen from the storage mite Acarus siro

• Published in: BMC biochemistry Vol. 13; no. 1; p. 3
• Main Authors: Pytelková, Jana, Lepšík, Martin, Sanda, Miloslav, Talacko, Pavel, Marešová, Lucie, Mareš, Michael
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 31.01.2012; BioMed Central
• Subjects: Acaridae - enzymology; Acaridae - immunology; Acarus siro; Allergens; Allergens - chemistry; Allergens - immunology; Allergens - isolation & purification; Allergies; alpha-Amylases - chemistry; alpha-Amylases - immunology; alpha-Amylases - isolation & purification; Amino Acid Sequence; Animals; Chloride; Cross Reactions; Cross-reactivity; Dermatophagoides pteronyssinus; Enzymatic activity; Enzymes; Epitopes; Feces - chemistry; Food contamination; Food hypersensitivity; Homology; Humans; Hypersensitivity; Hypersensitivity - blood; Hypersensitivity - immunology; Immunoglobulin E; Immunoglobulin E - blood; Immunoreactivity; Insect Proteins - chemistry; Insect Proteins - immunology; Insect Proteins - isolation & purification; Ions; Mites; Molecular Sequence Data; Physiological aspects; Protein Binding; Protein Structure, Tertiary; Proteins; Sequence Alignment; Stored products; Structural Homology, Protein
• ISSN: 1471-2091; 1471-2237; 1471-2091
• DOI: 10.1186/1471-2091-13-3

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. 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. 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.