Science1 publisher3 min readPublished
Figleaf gourd enzyme weakens peanut proteins' binding to allergy antibodies in Wroclaw lab tests
Wroclaw researchers report that a protease from figleaf gourd significantly cuts how well peanut proteins bind allergy antibodies in lab tests. Fragments of the potent allergens Ara h 2 and Ara h 6 still bound IgE, so nothing here is yet safe for allergic eaters.
The Scientist · Science desk
What happened
- Researchers at Wroclaw University of Environmental and Life Sciences and Wroclaw Medical University tested a figleaf gourd protease on peanut proteins, reporting in Food Chemistry.
- Hydrolysis significantly reduced immunoreactivity without eliminating it, leaving smaller fragments that IgE antibodies could still recognise.
- The allergens that kept their ability to react with antibodies after treatment included Ara h 2, Ara h 6 and Ara h 3.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- constraint The residual binding sits in the allergens already known to resist processing and digestion, so the hardest part of making a safe peanut ingredient is still unsolved.
- decision Process developers get a starting order of settings to optimise, time and temperature first, and heat is already paired with commercial enzymes in allergen-reduction work.
- exposure With anaphylaxis possible from small amounts, an ingredient still carrying IgE-binding fragments would put sensitised eaters at risk if sold on a reduced-allergen claim.
- capability A noncommercial plant protease that acts on both milk and peanut proteins adds an enzyme source beyond the commercial digestive preparations now used for hydrolysis.
Immunoreactivity, the quantity that fell, measures how readily the antibodies of an allergic response recognise a protein [1][2]. In allergic people those antibodies react with specific protein fragments called epitopes, and a protein's structure is one factor that decides whether they are recognised [7]. A protease that cuts in the right places should leave the antibodies less to find. "If enzymatic hydrolysis appropriately modifies protein structure, its ability to bind antibodies may be reduced. In the case of allergens, this approach is particularly interesting because it allows us not only to break down the protein, but above all to control changes in its properties," said Joanna Bajzert of Wroclaw University of Environmental and Life Sciences, an author of the paper [8].
Graded treatment suits this question. An effect that grows with enzyme exposure points to the enzyme and away from handling artefacts. The team prepared proteins from raw peanuts and ran the gourd protease on them under different conditions, and breakdown progressed the longer the enzyme worked [11]. Duration and temperature had the largest effect on immunoreactivity [12].
How large the reduction was is not reported. Nor does the account compare the gourd enzyme with the commercial digestive-enzyme preparations mostly used for protein hydrolysis [5]. Those preparations, used alone, in combination or with heat, can already significantly reduce the allergenicity of many proteins [5]. The gourd enzyme is a noncommercial extracellular serine protease. The same Wroclaw group had earlier shown that it breaks down milk proteins effectively [6][9].
The fragments that survived belong to the proteins a lower-allergen ingredient most needs to disarm. Ara h 2 and Ara h 6, two of the allergens that kept their antibody binding [14], are among the most potent peanut allergens and are relatively resistant to processing and digestion [10]. According to the report, conventional food processing alone may not be enough to reduce their allergenic properties significantly [10].
Partial reduction is a problem for an allergen that acts in small amounts. "Peanut allergy is particularly challenging because even a small amount of the allergen can trigger a serious reaction in sensitized individuals, including anaphylaxis. We are therefore looking for methods that can modify allergenic proteins and reduce their recognition by the immune system," said Ewa Willak-Janc of Wroclaw Medical University, a co-author [4]. The study has not produced a product that is safe for people with peanut allergy, the report says, though it points to a possible route to foods with reduced allergenic potential [3].
The experiments measured antibody binding, in lab tests [15]. Whether weaker binding in a lab assay would mean a milder reaction in a person is a second question. It would need testing in allergic people.
What to watch
- Publication of how large the immunoreactivity drop was, and whether it holds across antibodies from a broad group of peanut-allergic patients.
- An enzyme-plus-heat protocol that removes the remaining Ara h 2 and Ara h 6 fragments, or a head-to-head test against commercial digestive enzymes on peanut.
- Any move from antibody-binding assays to testing treated peanut protein in allergic people.