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Allergenicity and physicochemical characterization of house dust mite derived amylase
F R Lake1, L D Ward, R J Simpson
1Western Australian Research Institute for Child Health, Princess Margaret Hospital, Subiaco, Perth.
Abstract:
The enzyme amylase was shown to be present in extracts prepared from both house dust and spent growth medium used in the culture of the mite Dermatophagoides pteronyssinus. In dust, it was shown to correlate with both mite counts and concentrations of the faecally derived mite allergen, Der p I. Mite amylase was isolated from the culture medium and shown to be a single chain protein with a molecular weight of 56,000. The enzyme contained free sulphydryl groups and had the N-terminal sequence, KYXNPHFIGXRSVITXLME. It was found to be an allergen using sera from adults (46% positive) and children (25%) who were mite allergic. The expression of allergenicity was dependent on the integrity of intra-chain disulphide bonds.
Insights
House dust mite (Dermatophagoides pteronyssinus) amylase is present in dust and mite cultures. This mite enzyme is an allergen, with its allergenicity linked to its structure.
Area of Science:
- Biochemistry
- Immunology
- Allergology
Background:
- House dust mites (Dermatophagoides pteronyssinus) are a common source of indoor allergens.
- Mite-derived enzymes are implicated in allergic responses.
- Der p I is a major faecal allergen from Dermatophagoides pteronyssinus.
Purpose of the Study:
- To investigate the presence and characteristics of amylase in house dust mite extracts.
- To determine if mite amylase functions as an allergen.
- To explore the structural basis of mite amylase allergenicity.
Main Methods:
- Extraction and purification of amylase from mite culture medium.
- Molecular weight determination and N-terminal sequencing of mite amylase.
- Allergenicity testing using sera from mite-allergic adults and children.
- Assessment of allergenicity dependence on disulfide bond integrity.
Main Results:
- Amylase was detected in house dust and mite culture medium, correlating with mite counts and Der p I levels.
- Purified mite amylase is a single-chain protein (MW 56,000) with free sulfhydryl groups and a specific N-terminal sequence.
- Mite amylase demonstrated allergenicity in 46% of allergic adults and 25% of allergic children.
- Allergenicity was dependent on the integrity of intra-chain disulfide bonds.
Conclusions:
- House dust mite amylase is a potential allergen.
- The enzyme's structure, particularly disulfide bonds, is crucial for its allergenic activity.
- Further research into mite amylase may offer new insights into dust mite allergy mechanisms.